The meteor over Russia entered the Earth's atmosphere about 9:20 a.m. local time (10:20 p.m. EST Thursday) at a hypersonic speed of at least 33,000 mph (54,000 kph) and shattered into pieces about 30-50 kilometers (18-32 miles) high, the Russian Academy of Sciences said. NASA estimated its speed at about 40,000 mph and the energy released in the hundreds of kilotons.
"There was panic. People had no idea what was happening," said Sergey Hametov of Chelyabinsk, about 1,500 kilometers (930 miles) east of Moscow.
"We saw a big burst of light, then went outside to see what it was and we heard a really loud, thundering sound," he told The Associated Press by telephone.
The shock wave blew in an estimated 100,000 square meters (more than 1 million square feet) of glass, according to city officials, who said 3,000 buildings in Chelyabinsk were damaged. At a zinc factory, part of the roof collapsed.
The Interior Ministry said about 1,100 people sought medical care after the shock wave and 48 were hospitalized. Most of the injuries were caused by flying glass, officials said.
Emergency Situations Ministry spokesman Vladimir Purgin said many of the injured were cut as they flocked to windows to see what caused the intense flash of light, which momentarily was brighter than the sun.
There was no immediate word on any deaths or anyone struck by space fragments.
President Vladimir Putin summoned the nation's emergencies minister and ordered immediate repairs. "We need to think how to help the people and do it immediately," he said.
Some meteorite fragments fell in a reservoir outside the town of Chebarkul, the regional Interior Ministry office said. The crash left an eight-meter (26-foot) crater in the ice.
Lessons had just started at Chelyabinsk schools when the meteor exploded, and officials said 258 children were among those injured. Amateur video showed a teacher speaking to her class as a powerful shock wave hit the room.
Yekaterina Melikhova, a high school student whose nose was bloody and whose upper lip was covered with a bandage, said she was in her geography class when a bright light flashed outside.
"After the flash, nothing happened for about three minutes. Then we rushed outdoors. ... The door was made of glass, a shock wave made it hit us," she said.
Russian television ran video of athletes at a city sports arena who were showered by shards of glass from huge windows. Some of them were still bleeding.
Other videos showed a long shard of glass slamming into the floor close to a factory worker and massive doors blown away by the shock wave.
Meteors typically cause sizeable sonic booms when they enter the atmosphere because they are traveling so much faster than the speed of sound. Injuries on the scale reported Friday, however, are extraordinarily rare.
"I went to see what that flash in the sky was about," recalled resident Marat Lobkovsky. "And then the window glass shattered, bouncing back on me. My beard was cut open, but not deep. They patched me up. It's OK now."
Another resident, Valya Kazakov, said some elderly women in his neighborhood started crying out that the world was ending.
The many broken windows exposed residents to the bitter cold as temperatures in the city were expected to plummet to minus 20 Celsius (minus 4 Fahrenheit) overnight. The regional governor put out a call for any workers who knew how to repair windows.
Russian-language hashtags for the meteorite quickly shot up into Twitter's top trends.
"Jeez, I just woke up because my bed started shaking! The whole house is moving!" tweeted Alisa Malkova.
Social media was flooded with video from the many dashboard cameras that Russians mount in their cars, in case of pressure from corrupt traffic police or a dispute after an accident.
The dramatic event prompted an array of reactions from prominent Russians.
Prime Minister Dmitry Medvedev, speaking at an economic forum in the Siberian city of Krasnoyarsk, said the meteor could be a symbol for the forum, showing that "not only the economy is vulnerable, but the whole planet."
Vladimir Zhirinovsky, a nationalist leader noted for his vehement statements, blamed the Americans.
"It's not meteors falling. It's the test of a new weapon by the Americans," the RIA Novosti news agency quoted him as saying.
Deputy Prime Minister Dmitry Rogozin said the incident showed the need for leading world powers to develop a system to intercept objects falling from space.
"At the moment, neither we nor the Americans have such technologies" to shoot down meteors or asteroids, he said, according to the Interfax news agency.
Meteroids are small pieces of space debris usually parts of comets or asteroids that are on a collision course with the Earth. They become meteors when they enter the Earth's atmosphere. Most meteors burn up in the atmosphere, but if they survive the frictional heating and strike the surface of the Earth they are called meteorites.
NASA said the Russian fireball was the largest reported since 1908, when a meteor hit Tunguska, Siberia, and flattened an estimated 80 million trees. Chelyabinsk is about 5,000 kilometers (3,000 miles) west of Tunguska. The Tunguska blast, attributed to a comet or asteroid fragment, is generally estimated to have been about 10 megatons.
Scientists believe that a far larger meteorite strike on what today is Mexico's Yucatan Peninsula may have been responsible for the extinction of the dinosaurs about 66 million years ago. According to that theory, the impact would have thrown up vast amounts of dust that blanketed the sky for decades and altered the climate on Earth.
The 150-foot space rock that safely hurtled past Earth on Friday was dubbed Asteroid 2012 DA14.
The asteroid was invisible to astronomers in the United States at the time of its closest approach on the opposite of the world. But in Australia, astronomers used binoculars and telescopes to watch the point of light speed across the clear night sky.
Jim Green, NASA's director of planetary science, called the back-to-back celestial events an amazing display.
"This is indeed very rare and it is historic," he said on NASA TV. "These fireballs happen about once a day or so, but we just don't see them because many of them fall over the ocean or in remote areas. "
Experts said the Russian meteor could have produced much more serious problems in the area hosting nuclear and chemical weapons disposal facilities.
Vladimir Chuprov of Greenpeace Russia said the Russian government has underestimated potential risks of the region. He noted that the meteor struck only 100 kilometers (60 miles) from the Mayak nuclear storage and disposal facility, which holds dozens of tons of weapons-grade plutonium.
A chemical weapons disposal facility at Shchuchye also contains some 6,000 tons (5,460 metric tons) of nerve agents, including sarin and VX, about 14 percent of the chemical weapons that Russia is committed to destroy.
The panic and confusion that followed the meteor quickly gave way to typical Russian black humor and entrepreneurial instincts. Several people smashed in the windows of their houses in the hopes of receiving compensation, the RIA Novosti news agency reported.
Others quickly took to the Internet and put what they said were meteorite fragments up for sale.
One of the most popular jokes was that the meteorite was supposed to fall on Dec. 21, 2012 when many believed the Mayan calendar predicted the end of the world but was delivered late by Russia's notoriously inefficient postal service.
AP writers Max Seddon and Stephanie Nano contributed to this story. Sky fall: Meteorites strike Earth every few months
BERLIN • A meteor exploded in the sky above Russia's Ural Mountains on Friday, causing a shockwave that blew out countless windows and injured hundreds of people with flying glass. Here's a look at those objects in the sky:
Q. What's the difference between a meteor and a meteorite?
A. Meteors are pieces of space rock, usually from larger comets or asteroids, which enter the Earth's atmosphere. Many are burned up by friction and the heat of the atmosphere, but those that survive and strike the Earth are called meteorites. They often hit the ground at tremendous speed up to 30,000 kilometers an hour (18,650 mph) releasing a huge amount of energy, according to the European Space Agency.
Q: How common are meteorite strikes?
A: Experts say smaller strikes happen five to 10 times a year. Large impacts such as the one Friday in Russia are rarer but still occur about every five years, according to Addi Bischoff, a mineralogist at the University of Muenster in Germany. Most of these strikes happen in uninhabited areas where they don't injure humans.
Q: How big was Friday's bang in Russia, and why did it cause so many injuries?
A: Alan Harris, a senior scientist at the German Aerospace Center in Berlin, said most of the damage would have been caused by the blast or blasts as the meteor broke up in the atmosphere. The rapid deceleration of the meteor released a huge amount of energy that would have been heard and felt many miles away. Witnesses say it shattered windows and sent loose objects flying through the air.
While estimates of the mass of the meteor range from 10-100 tons, and it is still unclear if it was made of rock or iron, "the explosive force of the airburst might have been some 10 kilotons of TNT," said Harris. But he noted that since the blast occurred several miles above the Earth, the damage isn't comparable to an explosion of that magnitude on the Earth' surface.
By comparison, the U.S. bomb dropped over Hiroshima during World War II had an explosive force of about 15 kilotons, but it detonated just 2,000 feet above a densely populated city.
Q: Is there any link between this meteor and the asteroid fly-by taking place later Friday?
A: No, it's just cosmic coincidence, according to European Space Agency spokesman Bernhard von Weyhe, who says Asteroid 2012DA14 is unrelated to the meteorite strike in Russia.
Q: When was the last comparable meteorite strike?
A: In 2008, astronomers spotted a meteor heading toward Earth about 20 hours before it entered the atmosphere. It exploded over the vast African nation of Sudan, causing no known injuries.
The largest known meteorite strike in recent times was the "Tunguska event" that hit Russia in 1908. Even that strike, which was far bigger than the one that happened over Russia on Friday, didn't injure anyone.
Scientists believe that an even larger meteorite strike on what today is Mexico's Yucatan Peninsula may have been responsible for the extinction of the dinosaurs about 66 million years ago. According to that theory, the impact would have thrown up vast amounts of dust that blanketed the sky for decades and altered the climate on Earth.
Q: What can scientists learn from Friday's strike?
A: Bischoff says scientists and treasure hunters are probably already racing to find pieces of the meteorite. Some meteorites can be very valuable, selling for up to $670 per gram, depending on their origin and composition. Because meteors have remained largely unchanged for billions of years unlike rocks on Earth that have been affected by erosion and volcanic outbreaks scientists will study the fragments to learn more about the early universe.
Harris, of the German Aerospace Center, says some meteorites are also believed to carry organic material and may have influenced the development of life on Earth.
Q: What would happen if a meteorite hit a major city?
A: Scientists hope never to find out, but they have been trying to prepare for such an event anyway. Von Weyhe, the European Space Agency spokesman, says experts from Europe, the United States and Russia are already discussing how to spot potential threats sooner and avert them. But don't expect a Hollywood-style mission to fly a nuclear bomb into space and blow up the asteroid, like the movie "Armageddon."
"It's a global challenge and we need to find a solution together," he said. "But one thing's for sure, the Bruce Willis "Armageddon" method won't work."
The Associated Press