The temblor terrified many of the thousands who have been living in tents or cars since the May 20 quake and created a whole new wave of homeless.
''I was shaving and I ran out very fast, half dressed," a resident of Sant'Agostino, one of the towns devastated in the quake earlier this month, told AP Television News.
Tuesday's quake struck just after 9:00 a.m. with an epicenter 25 miles northwest of Bologna, according to the U.S. Geological Survey just a handful of miles away from where the 6.0-magnitude quake that killed seven people on May 20 was centered.
Government undersecretary Antonio Catricala, briefing the Senate in Rome, said at least 15 people were killed, some 200 injured and seven people missing. The number of homeless swelled by several thousand, to a total of 14,000, he said.
While Tuesday's quake was about 100 times less intense than the one May 20, its death toll was more than twice as high. In both, the dead included workers killed by collapsing factories and warehouses.
In the town of Mirandola, near the epicenter, the church of San Francis crumbled, leaving only its facade standing. The main cathedral also collapsed.
Sant'Agostino's town hall, so damaged in the May 20 quake that it looked as if it had been bombed, virtually collapsed when the latest deadly temblor struck.
In a hastily called news conference, Premier Mario Monti pledged the government will do ''all that it must and all that is possible in the briefest period to guarantee the resumption of normal life in this area that is so special, so important and so productive for Italy."
The region around Bologna is among the country's most productive. Italy is desperately in need of its industries, for the country is in the midst of another recession and struggling to tame its massive debt as the European debt crisis worsens.
Many victims of the new quake, like the one nine days ago, were at work in huge warehouses that collapsed, including one dead inside a machinery factory in Mirandola.
Labor Minister Elsa Fornero suggested the destruction to buildings was out of proportion, considering the magnitude of the quake.
''It is natural that the earth shakes. But it is not natural that buildings collapse," Fornero said, briefing lawmakers in the lower Chamber of Deputies in Parliament.
The mayor of San Felice sul Panaro told Sky News 24 that there were fatalities in his town, where Italian media said a tower had collapsed.
Tall buildings and schools were evacuated as far away as Milan as a precaution before people were allowed to re-enter. Train lines connecting Bologna with other northern cities were halted while authorities checked for any damage.
When the quake hit, Monti was meeting with emergency officials in Rome to discuss the impact of the earlier quake, which struck in the middle of the night and left at least 7,000 homeless.
The May 20 quake was described by Italian emergency officials as the worst to hit the region since the 1300s. In addition to the deaths, it knocked down a clock tower and other centuries-old buildings and caused millions in losses to a region known for making Parmesan cheese. Its epicenter was about 22 miles north of Bologna.
It's not clear why two large quakes have appeared just this month, said Jessica Turner, a geophysicist with the U.S. Geological Survey in Golden, Colo. The basic driver of the activity is the same kind of geological shifting that produced the Alps, she said.
Prior to May 20, the last earthquake in the region with magnitude that large was in 1501.
Residents had just been taking tentative steps toward resuming normal life when the second quake struck. In Sant'Agostino, a daycare center had just reopened.
In the town of Concordia, the mayor had scheduled a town meeting Tuesday evening to discuss the aftermath of the first quake. Instead, mayor Carlo Marchini confirmed the death of one person struck by falling debris in the town's historic center.
Italy's friendly soccer match against Luxembourg, a warm-up match for the Euro 2012 championships, was canceled. The game had been scheduled to be played Tuesday in Parma, just 40 miles west of the quake.