A search was on Thursday night for nine people left missing after a Coast Guard plane collided with a Marine helicopter over the Pacific Ocean near Southern California, officials said.

Rescuers were combing the area where the collision occurred, aviation officials said.

A pilot reported seeing a fireball about 7:10 p.m. near the crash site, which is about 25 miles east of San Clemente Island. FAA officials said a Coast Guard C-130 plane carrying seven people collided with a Marine Corps AH-1 Cobra helicopter carrying two people.