LOS ANGELES, USA - Rescuers scouring the Pacific Ocean off the California coast Saturday found the wreckage of a transport plane and helicopter that collided, but no sign of the nine people feared dead in the crash.

Remains of the Coast Guard C-130 plane with seven people aboard, and the Cobra helicopter belonging to the US Marines with two aboard were found near San Clemente Island, off the coast of San Diego in the state's southwest.

Rescuers said that no human remains had been spotted in the debris field.

Wreckage flotsam was found scattered over a five-by-12 mile (eight-by-19 kilometer) area, in a spot where the ocean is some 2,000 feet (610 meters) deep, officials said.

Six Coast Guard cutters, three US Navy ships and various aircraft searched for survivors, as Coast Guard San Diego sector commander Captain Tom Farris said Saturday that the team remained in a "search-and-rescue phase."

Pentagon spokesman Bryan Whitman, who described the crash as a "tragic event," however told reporters Friday that the nine missing people were "likely" dead.

Military officials said that the AH-1 Super Cobra helicopter was based at the Marine Corps Air Station Miramar, while the Coast Guard said that its HC-130 plane came from a base in the state capital Sacramento.

The Coast Guard said its plane was in the area searching for a 50-year-old missing boater from Santa Catalina Island, last seen leaving harbor late Tuesday on a motorized skiff. The boater is still missing.

The Marine helicopter crew was heading to a nearby island, San Clemente, which is controlled by the navy, on a training mission. The planes collided after sundown, around 7:10 local time, officials said.

The aircraft were in a patch of airspace the Federal Aviation Administration (FAA) has set aside for military exercises, and pilots are supposed to notify ground controllers when they enter the area.

It is the third accident involving a military helicopter in the region this year. On May 5, two Marines died when their Super Cobra helicopter crashed in a California forest during a training flight, and five crew died when a Navy HH-60H Seahawk helicopter crashed into the Pacific on May 19.

Officials at the southern California Marine Air Wing said they suspended all flights through the weekend to re-emphasize safety measures.

Both the Marines and the Coast Guard on Saturday released the names of the missing personnel.