SAN DIEGO -- A scuba diver who lost consciousness and went into convulsions off La Jolla shores Sunday was rescued by lifeguards who said his quick-acting diving buddy saved his life.

The 35-year-old Orange County man went into convulsions at 12:15 p.m. when he inhaled a toxic amount of oxygen in 15 feet of water, said Lt. Andy Lerum of the San Diego Lifeguard Service.

The diver was using an advanced diving technique involving mixed gases that allows divers to stay underwater for longer periods.

His diving buddy saw the convulsions and quickly transferred his regulator to his friend, which Lerum said saved the other diver's life.

Even though the divers were only at a depth of about 15 feet, he could have died because convulsions trigger choking, Lerum said.

Lifeguards administered first aid, then transported the man to UCSD Medical Center, where he was doing fine, Lerum said.

Lifeguards were alerted to the incident by a flare. It was not known what went wrong with the diver's air supply.