Rocket carrying spy satellite launches from Calif.

VANDENBERG AIR FORCE BASE, Calif. • A massive rocket carrying a spy satellite for the U.S. government launched from the central California coast Wednesday.

The Delta IV Heavy rocket soared off the launch pad at Vandenberg Air Force Base, about 150 miles northwest of Los Angeles, and sped toward low-Earth orbit, officials at United Launch Alliance said.

The rocket carried a satellite for the National Reconnaissance Office, which oversees the nation's constellation of intelligence-gathering satellites. Liftoff occurred at 11:03 a.m. PDT, about 10 minutes later than planned as engineers dealt with some last-minute minor issues.

Since the mission is classified, no other details were available.

At 23 stories, the Delta IV Heavy is the largest rocket in the country. The last time it launched from Vandenberg — in 2011 — the roar of the engines shook the nearby city of Lompoc. Some people reported hearing the engine roar from 50 miles away.

This time around, the three main engines were ignited one after another to lessen the impact during liftoff.

Air Force security and police closed a nearby beach and evacuated campers as a precaution. About 200 cars lined the access road to the base and spectators gathered at other viewing spots for a glimpse of the rocket cruising through the cloudless sky.

United Launch Alliance is a joint venture of Lockheed Martin Corp. and The Boeing Co. to provide space launch services to the federal government with their Atlas and Delta rocket programs.