Around 200 firefighters backed up by helicopters battled to contain a huge fire today at Universal studios in Los Angles.

There were no immediate reports of injuries but the blaze had destroyed several film sets, including mock-ups of New York and New England streets.

Los Angeles County fire inspector Daryl Jacobs said at least one building had burned down, and as many as three blocks of film sets were consumed by flames. There was at least one explosion.

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.

Firefighters were trying to prevent the flames from spreading to nearby brush, according to fire captain Frank Reynoso. He told CNN that the blaze broke out just before dawn on a sound stage, and added: "We don't know what the cause of this is."

A thick column of smoke rose thousands of feet into the air. For a time, firefighting helicopters swept in to drop water.

Burbank firefighter David Ortiz told Reuters that 200 firefighters and two helicopters had been deployed.

Universal spokesman Elliot Sekuler said filming was going on when the fire started but had no further details.

Universal studios is located nine miles north of central Los Angeles. It includes working TV and film studios, as well as a theme park featuring rides and the house featured in Alfred Hitchcock's Pyscho.