A federal law enforcement officer was killed when a dope smuggler's small craft rammed a Coast Guard boat in a midnight intercept of a marijuana load off the California coast, law enforcement sources told ABC News.

Four suspects are in custody and a manhunt is under way for at least two others who may have escaped to a coastal island.

According to sources, the incident took place early this morning, at approximately 1 a.m., when the Coast Guard intercepted two boats - a pleasure craft and a panga boat, which is a small, fast launch - near San Clemente Island, in Santa Barbara County.

The Coast Guard, according to initial reports, took the pleasure craft into custody and detained two occupants.

The Coast Guard cutter crew then lowered their smaller boat into the water in order to take custody of the individuals on the panga boat.

At that point the operation turned deadly.

As the Coast Guard small craft approached the panga, the driver of the panga rammed it and actually drove over the top of the boat, striking two agents and killing one of them.

Other members of the Coast Guard team took the occupants of the panga into custody, making for a total of four suspects in custody - two from the pleasure craft and two from the panga.

Sources said that authorities believed that two additional suspects were dropped off on Santa Cruz Island just before the interception of the two boats.

The Santa Barbara Sheriffs SWAT team was working with the U.S. Border Patrol today, searching Santa Cruz Island for additional suspects.

The small Coast Guard Boat that was rammed was taken to Oxnard.

Coast Guard officials said they planned to transport this boat, as well as the pleasure craft and panga boat to the Coast Guard Base in the Port of Los Angeles.

According to sources, the Coast Guard Investigative Services are requesting assistance from the Los Angeles Police Department Scientific Investigation Division forensics unit and photo unit.

Arrangements are under way to secure the vessels at the Port until Monday morning, when SID can respond.

The panga was operated by Mexican nationals, and the cargo was marijuana, law enforcement sources said.