Less than a week after a house fire killed his 19-year-old son, San Ramon doctor Robert Litman was released from the hospital Sunday, where he was being treated for smoke inhalation injuries.

Hospital officials could not elaborate on Litman's condition.

Fire inspectors believe the 68-year-old allergy specialist and his son, Benjamin Litman, likely did not have time to escape from their Blackhawk home June 22 because the fire started in the attic and didn't trigger any alarms in time.

It is unclear how long the fire was burning in the attic, said San Ramon Valley Fire Protection District Chief Richard Price.

"When it finally broke through to the bottom floor it was already burning for a while," said Price. "It could have been burning for hours in that attic or it could have been burning for half an hour."

Fire district investigators found that the blaze probably grew undetected by the home's alarm system on the ground floor until flames broke through the second-floor ceilings, hurling rubble into the rooms below.

An autopsy last week found that the Benjamin Litman, a senior at an alternative high school in San Ramon, died from breathing in smoke, said Contra Costa County Sheriff spokesman Jimmy Lee.

Theresa Patterson, a longtime friend of the Litmans who lives nearby, said she never smelled any smoke or heard any commotion coming from the burning home the evening of the fire.

"It's embarrassing to say I slept through the whole thing," she said. "It's a tragedy.  All the neighbors are beside themselves."

Price said attic fires are uncommon, so smoke detectors aren't installed there.

"It is a very uncommon place for a fire to start because there is very little up there to start a fire," said Price."It would be very uncommon to have a smoke detector in the attic. You are subject to false alarms with stuff like spiders, dust and vents in the attic."

Price said it is not yet known if the home had other smoke detectors in addition to the main alarm system on the ground floor.

"The big message for us is that smoke detectors should be in the bedrooms and hallways on every floor," he said. "That could have made a difference here."

Investigators are still trying to determine what started the fire in the attic of the more than 5,000-square-foot two-story home at 2978 Deer Meadow Drive.

The San Ramon Valley Fire Protection District responded to the call from a fire alarm monitoring company reporting a smoke detector activation. When fire crews arrived they found the roof of the home covered with flames.

Crews responded with six engines, two trucks, two paramedic ambulances, four chief officers, one safety officer and two fire investigators.

The home sustained about $2 million in damages and lost contents.