SAN FRANCISCO -- A young man found dead in a burning residential building in the Bayview neighborhood Thursday morning has been identified by the San Francisco medical examiner's office as Liberio Sanchez Jr.

Sanchez was a San Francisco resident. His age was not immediately available from the medical examiner, but San Francisco fire Lt. Mindy Talmadge said he is believed to be 18 or 19.

Sanchez's cause of death has not been determined and the cause of the fire remains under investigation.

The blaze at 1649 Palou Ave. was reported at 3:06 a.m. and almost immediately went to a second alarm, Talmadge said.

"When the first units get there, the first thing they do is search and rescue. They sent a couple teams of people in but it was difficult going in with the heavy fire," Talmadge said.

Sanchez was found dead inside the building, authorities reported.

Firefighters were able to control the blaze by 3:45 a.m., Talmadge said. By then, however, fire had damaged two nearby residential structures, 1653 and 1655 Palou Ave., which is one building, and 1641 Palou Ave.

The building where the fire broke out and where Sanchez was found dead sustained about $200,000 in damage to its structure and $20,000 to its contents, Talmadge said.

She estimated damage to the neighboring structure at 1653 and 1655 Palou Ave. at $40,000 to the building and $20,000 to its contents. The structure at 1641 Palou sustained $6,000 in damage, mainly to its exterior, Talmadge said.

The fire displaced 24 people living in the two most heavily damaged buildings, Talmadge said. The American Red Cross is assisting the fire victims.