5 Firefighters Injured as Roof Collapses : Blaze: Old building in downtown commercial district burns. Earlier fire is believed to have weakened structure.

Five firefighters were injured--one of them seriously--when the roof of a burning building in the downtown commercial district collapsed on them.

“Suddenly I heard a big boom and the whole thing just started coming down at once,” said Shirley Miller, the principal of nearby Metropolitan High School, who watched firefighters battle the blaze in the vacant, one-story brick building in the 800 block of South Mateo Street.

“They heard a ‘crack’ and they started running,” said Deputy Fire Chief Donald Anthony. “One of the men was trapped under the fallen roof. They had to dig 30 feet to get to him. He was buried for 10 minutes.”

Anthony said the buried man suffered a broken left leg and possibly a fractured ankle, while the other men had lesser injuries--”sprains, aches, things like that.”

All five were transported by ambulance to White Memorial Medical Center, where their conditions were all listed as stable. The names of the firefighters were not released, pending notification of their families.

The cause of the blaze was not immediately determined, but Anthony said it may have been sparked by a cooking fire lit by transients, who occupy many of the boarded-up buildings in the area at night.

Miller said she spotted Friday’s fire shortly after coming to work and immediately called the Fire Department. Fire companies responding to the call at 7:07 a.m. found flames shooting up through the roof of the aging building.

Anthony said the building was constructed of unreinforced masonry, probably before the 1933 Long Beach earthquake. Laws enacted since then have required reinforcement of all new buildings, but many old structures have not been upgraded.

The deputy chief said an earlier fire probably had weakened some of the roof beams in the building, but the damage had not been detected.

“This morning’s fire did not appear to be all that significant,” Anthony said. “But previous damage from the earlier fire, and damage today, apparently did it.”

He said two of the firefighters in the building managed to flee before the roof fell on them, but the five others--two of them captains--were struck by the falling debris.

Because of the danger of additional collapse, the firefighters retreated to the roofs of adjacent buildings to continue their battle against the stubborn blaze. The last of the flames were finally extinguished at about 8:30 a.m.