The blaze in the 4500 block of Campus Avenue erupted about 10 a.m., according to the San Diego Fire-Rescue Department.
It took about two dozen firefighters just under 15 minutes to extinguish the flames, which caused extensive damage to the second-floor residence and sent smoke into a neighboring unit, SDFRD spokesman Maurice Luque said.
Crews found two small dogs and a cat dead inside the charred second- floor residence, he said. The resident was at work when the blaze broke out.
The cause of the fire was an unattended candle left burning in a bedroom, investigators said. Damage from the fire was estimated at $150,000 to the structure and $50,000 to the contents.