(AP) -- June 1, 2008 -- A massive fire raged on a back lot at Universal Studios early Sunday, spewing thick smoke as it devoured blocks of movie sets. There were no immediate reports of injuries.

Los Angeles County fire Inspector Daryl Jacobs said at least one building had burned and as many as three blocks of movie facades were destroyed. Though the fire was contained, it was still raging, Jacobs said.

"The facades are constructed of heavy timber and they tend to burn quite freely," he said.

The blaze broke out just before dawn on a sound stage, fire Capt. Frank Reynoso said. A thick column of smoke rose thousands of feet into the air. For a time, firefighting helicopters swept in to drop water.

More than 100 firefighters were trying to prevent the flames from spreading to nearby brush, Reynoso said.

Filming might have been going on at the time the fire broke out and there was at least one explosion, Reynoso said.

Universal City is nine miles northwest of downtown Los Angeles.