Firefighter and paramedic Anthony "Tony" Valerio, 53, one of the three firefighters involved in the deadly fire in Diamond Heights on Friday, died on Saturday morning at about 7:30 a.m. Valerio, a Bay Area native, spent 13 years with the city's Department of Public Health and 14 years with the fire department.

The fire also claimed the life of Lt. Vincent Perez, 48, on Friday. A third firefighter involved also suffered smoke inhalation but was treated and released from the hospital.

KGO has details about the incident, reporting that the fire had initially looked small when the firefighters first entered the home. Then all of a sudden the house was engulfed in smoke, which quickly turned black, and the fire appeared to be on the floor below the three firefighters. Investigators are still trying to determine whether the sudden intense heat that badly burned the two firefighters was caused by a "flashover," or a sudden ignition of objects in a room due to the increased levels of oxygen, as other firefighters were cutting holes in the walls and ceiling in order to ventilate the house.

Fire Chief Joanne Hayes-White said this was the first time in eight years that a firefighter was killed in the line of duty, and the first time in 65 years that a fire claimed the lives of more than one firefighter.