Dr. Robert Litman and his 19-year-old son Benjamin likely did not have enough time to escape a fire in their Blackhawk home Tuesday night because it started in the attic, according to a press release issued by the fire district Thursday morning.

Investigators from the San Ramon Valley Fire Protection District team found that the fire likely grew undetected until flames broke through the second floor ceilings, sending debris into the rooms below.

When the smoke detector in the house went off, the fire was already freely burning at an advanced stage, giving the Litmans little time to react.

Benjamin, a senior at Venture School in San Ramon, was found dead in the home by firefighters. His father, San Ramon-based physician Robert Litman, was found unconscious inside the home from smoke inhalation and remains hospitalized in Santa Jose.

Inspectors have not determined what in the attic caused the fire "due to the amount of destruction at the point of origin."

The fire swept through the more than 5,000-square-foot two-story home at 2978 Deer Meadow Drive in Blackhawk around 11:15 p.m. Tuesday.

The two family dogs were also killed in the fire.

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 approximately $1.5 million in damage and $500,000 in lost contents.

According to a website for Robert Litman, he is a 62-year-old family physician in San Ramon specializing in allergy care.

Staff answering the phone at his Norris Canyon Road office Wednesday said they did not want to comment.

The Contra Costa County Coroner said an autopsy would be conducted on Benjamin Litman Thursday.