Three firefighters are injured as crews battle the blaze for about two hours.
A fire set off several explosions early Wednesday at a building complex on East Slauson Avenue.
Crews battled the blaze for about two hours amid the debris-laden blasts and collapsing walls fire crews.
Two firefighters, one of them a captain, sustained hand burns in one of the blasts, Cecil Manresa of the Los Angeles Fire Department said. They also experienced ringing in the ears and they went to hospitals to get checked out, Manresa said.
Six task forces and a total of up to 100 firefighters remained at the scene for hours Wednesday because at least one of the structures contained metal alloys including titanium and magnesium, a city fire dispatcher said. The cause of the fire was not immediately determined.
"You can't put water on titanium," LAFD Capt. Gail Manning said. "They're going to have to let the metal burn. It's going to be a bulldozer operation."
Close to 100 firefighters initially responded to the 11:43 p.m. blaze reported at 731 E. Slauson Ave., Manresa said. By 2 a.m. there were about 220 firefighters at the scene, Manresa said.
Fire crews were ordered out of the building at 12:03 a.m. to fight the fire in defensive mode -- from the outside.
Two minutes later commanders at the scene reported a wall collapsing and at 12:10 a.m. part of the roof caved in, Manresa said.
An explosion at 12:25 a.m. shook the burning complex, rained debris on fire crews and shattered emergency vehicle windows. Fire commanders ordered head counts to assess possible injuries. The two injured firefighters were assessed at the scene before they were taken to hospitals.
"Many of you have seen at the brush fires the ember storms we experience," LAFD Deputy Chief Mario Rueda said. "That is exactly what we experienced here.
"As a result of these explosions, titanium chips dispersed over the neighborhood. Large chunks of concrete impacted some of our apparatus and the concussive effect knocked out some of our windows, also of apparatus."
Rueda said titanium golf club heads were manufactured inside the building.
By 12:35 a.m. the blaze had spread to at least one adjoining building and ladder crews set up at 5715 McKinley Ave., Manresa said.
Nearby palm trees exploded in flames.
Fire crews stayed out of the buildings but used alleys between the structures to knock down parts of the fire, according to reports from the scene.
The complex of buildings appeared to span an entire block from McKinley to Poloma Avenue, Manresa said.