PITTSBURG -- A firefighter injured while searching a Pittsburg home after a two-alarm fire Monday remains in guarded condition at a hospital in San Pablo, the Contra Costa Fire Protection District reported Wednesday.

The firefighter was in the process of searching the home at 1231 Alamo Way for possible victims when a portion of the ceiling collapsed, knocking off his helmet and facemask, said Fire Chief Richard Carpenter.

Carpenter said the firefighter remains in guarded condition at Doctors Medical Center in San Pablo because upper respiratory injuries from heat and gas take a while to develop. He suffered burns to his face and head.

Two other firefighters suffered injuries while fighting the blaze, Carpenter said. One firefighter received a cut on his leg. He was treated at John Muir Hospital in Walnut Creek and released that night. The other firefighter was treated on the scene for a hand injury.

The fire caused $340,000 in damage to the home, Carpenter said. The fire has been ruled as accidental, and was most likely started outside by discarded barbecue coals.

No other injuries were reported. The fire, which was reported at 10:57 p.m. Monday, was under control by 12:10 a.m. Tuesday.