A 19-year-old U.S. Marine shot while on weekend leave in Los Angeles is on life support and unlikely to survive, and police were searching for suspects.

At least one person fired on Carlos Segovia after pulling up beside his car, Officer Norma Eisenman said Monday.

Segovia was found Friday night slumped over in the driver's seat of his car in South Los Angeles on Friday night, was unlikely to survive, officials said.

A vehicle pulled up beside Segovia's car, and at least one person opened fire, striking him once in the head, Officer Norma Eisenman.

A family friend, Claudia Perez, told the Los Angeles Times (http://lat.ms/2cCJbf0 ) that the Marine was visiting family and friends while on leave from Camp Pendleton near San Diego.

Segovia had spent time with his girlfriend and was on his way to Perez's home, where he usually stays while in Los Angeles, when he was struck by gunfire, she said.

"He texted my son that he was bringing pizza home. He never made it," Perez said.

Police notified the U.S. Marine Corps, which in turn notified Segovia's family about the shooting. Los Angeles police Capt. Peter Whittingham said Segovia is unlikely to survive and had little to no brain function.

Perez said Segovia is being kept on life support but acknowledged that the family will have to make a decision about ending medical care.

"He's fighting for his life," she added.

Segovia was not in uniform when he was shot. No suspects have been identified and investigators did not have a motive.

Police said Segovia has no connections to gangs or other activity that would seem to make him a likely target of gun violence.

Born in El Salvador, Segovia came to the U.S. with his mother. Both are U.S. citizens, Perez said.

He joined the Marines about six months ago after finishing high school.