LOS ANGELES (AP) _ An explosion and fire at a three-story residential complex in the San Fernando Valley on Friday injured three people, one of them critically.

FBI and police bomb experts responded as a precaution. Authorities said there was no indication of what had caused the late-morning blast or that there was any connection to a recent federal warning that terrorists could target the nation's apartment buildings.

``We have a bomb technician going to the scene with several agents, as is routine in a situation like this. But it's just a precaution. There is absolutely no indication there's any link to terrorism,'' said FBI spokeswoman Laura Bosley.

The explosion hurled debris around the suburban Encino neighborhood, about 15 miles northwest of downtown. A dozen units in the building were damaged.

``All I could see was black smoke. The sky was black. It was a really spooky scene,'' said resident Eileen Kessel, 62.

``I thought it was an earthquake but there was no aftershock,'' said Bob Morris, 52, who was in a building on the other side of the block at about 11 a.m. when the explosion happened.

Fire Department Battalion Chief Roberto Franco said one victim was in critical condition but he could not immediately confirm details of the injuries or the names of the victims.

The fire burned furiously for about an hour, sending a towering column of dark smoke over the south side of the valley. More than 130 firefighters and a dozen ambulances were dispatched to the building.

Everett Betts, who lives in a neighboring complex, said the complex was evacuated quickly. One evacuee was in a wheelchair.