Firefighters at San Jose Station No. 4, which is located on Leigh Avenue, could see the smoke from the station, he said.

"They called a second alarm before they even got out of the truck," Manley said.

The fire escalated to a fourth alarm as stations 4, 6 and 30 responded, bringing 50 firefighters to the site, he said. Firefighters fought the blaze with hoses that carried 4,000 gallons a minute and put out the fire after three hours, Manley said.

The 8,000-square-foot building sits on the corner of Meridian Avenue and Pedro Street near several apartment buildings.

The building was home to tenants Tri County Apartment Owners Association and Labor Connection, a temporary-job placement agency.

Manley said no surrounding residences were evacuated and the department had crews patrolling the neighborhood to watch for flying embers.

Two firefighters were treated for first-degree facial burns, and a third firefighter received a second-degree burn on his hands. Two injured firefighters were transported to Valley Medical Center and released three hours later, and all returned to work the next day, he said.

A week after the fire, the cause is still under investigation, said San Jose Fire Department spokeswoman Capt. Allison Cabral.

According to Manley, the fire went through the attic before the roof collapsed on the building, which was built in the 1950s, he said.

"The fire code was different then," Manley said. "It required 10,000 square feet to have sprinklers; now it's 5,500 square feet."