LA JOLLA — The cause of a boat fire off La Jolla Cove last week remains uncertain. Lifeguards and the U.S. Coast Guard rescued two people from their 31-foot Maxim power boat that caught fire about three miles off shore from La Jolla Cove on July 23. Lifeguard Lt. Nick Lerma said no injuries were reported as a result of the incident, and that the cause of the fire was not determined beyond speculation by the boat owners. “The owners believed it was an electrical fire started somewhere near the battery,” he said. Dispatch response began when a lifeguard in an observation tower noticed black smoke shortly before 11 a.m. A Coast Guard cutter responded in addition to four lifeguard rescue boats and personal rescue crafts. The people on board the flaming boat, meanwhile, jumped from their vessel into a dinghy and were picked up by a nearby sailing vessel, Lerma said.