SAN DIEGO -- Investigations were under way Friday to determine what caused two homes in separate areas of San Diego to catch fire, leaving some $650,000 in damages but no injuries, a fire department dispatcher said.

The first fire broke out in the 1200 block of Colusa Street in Linda Vista shortly after 7 p.m. Thursday, according to a San Diego fire-rescue dispatcher. It caused about $150,000 damage, but no one was hurt, she said.

The second fire, in the 12900 block of Rife Way in Rancho Penasquitos, was reported shortly before 11:30 p.m. Thursday, the dispatcher said, adding that damage was estimated at $500,000, but again, no one was hurt.

The home is owned by Scott Russo, singer for the band 'Unwritten Law'.

Russo said his daughter left her electric heater on while she was in the shower and the heater may have started the fire.

In each of the two fires, it took firefighters about 30 minutes to knock down the flames, the dispatcher said.