SAN DIEGO -- A man and his dog escaped unharmed from his burning apartment in City Heights early Thursday, but his cat perished in the blaze, which was sparked by a discarded cigarette, a San Diego fire official said.

The fire broke out about 7:30 a.m. on the second floor of a two-story apartment building at 4250 Swift Ave., near El Cajon Boulevard, said Maurice Luque of the San Diego Fire-Rescue Department.

Firefighters kept the flames from spreading to adjacent units, according to Luque, who said damage was estimated at $30,000 to the structure and $15,000 to personal property.

He said investigators determined that a discarded cigarette started the blaze.

The American Red Cross was assisting the victim with housing and other interim needs, Luque said.