SAN DIEGO -- A predawn arson fire gutted a Lake Murray-area house Thursday, causing nearly $850,000 worth of damage, authorities reported.

The non-injury blaze in the 6800 block of Wallsey Drive erupted shortly before 2 a.m., according to police and the San Diego Fire-Rescue Department.

Firefighters arrived to find flames fully engulfing the home's garage and aggressively spreading into the living quarters, SDFRD spokesman Maurice Luque told reporters.

It took crews about 15 minutes to extinguish the fire.

Federal investigators found evidence revealing that the blaze was a criminal act, Luque said.

"It was a deliberately set fire," he said. "We can say that much at this point in time."

The SDFRD spokesman declined to elaborate on what led to that conclusion.

The family that lives in the home was away on vacation when it went up in flames, 10News reported.

Authorities set the monetary losses at $500,000 to the house and $300,000 to furnishings and other valuables. The blaze also caused about $45,000 worth of damage to a neighboring residence, Luque said.