LOS ANGELES (AP) _ The cause of a late-night collision between a Navy tanker and an 80-foot sportfishing boat carrying 43 passengers and crew members was under investigation, officials said Friday.

Seven fishermen were injured in the accident late Thursday outside Los Angeles Harbor. A small amount of fuel leaked from the 538-foot tanker, which was carrying 7.8 million gallons of jet fuel, officials said.

The fishing vessel Shogun, a San Pedro-based charter, and the San Francisco-bound tanker Sealift Antarctic were returned to the Los Angeles port and the Coast Guard began an investigation.

The 80-foot Shogun remained afloat despite its run-in with the tanker about two miles outside the harbor, said Coast Guard Petty Officer Robert Beals.

Lifeguards from Long Beach rescued all those aboard the charter boat, including six crew members, and took them to shore in rescue boats, said Chief Petty Officer Mark Kennedy.

The four most seriously injured people were taken to St. Mary's Hospital in Long Beach, he said. Three were treated and released and the second mate was admitted for observation, said nursing supervisor Todd Brabbin.

The collision punctured the tanker's hull, producing a hole about the size of a quarter and spilling about 1,680 gallons of fuel, Dickerson said. The leak was quickly contained, he added.

The Antarctica, owned by the Irving Trust Co. of New York, operates under Navy charter to transport jet fuel, Kennedy said. It was manned by a merchant marine crew of 24.