AGANA, Guam (AP) _ Thick underbrush, rocky terrain and bodies charred beyond immediate identification all posed obstacles Wednesday to teams investigating the Korean Air crash.

The Boeing 747 from Seoul, South Korea, hit the ground Wednesday in a deep ravine three miles from the airport on this U.S.-governed Pacific island.

The flight data recorder and cockpit voice recorder were recovered and shipped Wednesday for analysis at the National Transportation Safety Board in Washington.

On-scene investigators from the NTSB and the Los Angeles County coroner's office, who began arriving Thursday, were forced to struggle through the sharp saw grass. The terrain was so slippery that it took government and military rescuers four hours to get survivors to a hospital only a mile away.

The tail of the Korean Air aircraft, brightly marked with the airline's blue and red logo, was one of the few recognizable pieces of the airplane. Smaller pieces were strewn across the high grass and rocks, which glistened, wet from the rain that was pouring down at the time of the crash.

Guam Gov. Carl Gutierrez lives near the crash site and was among the first on the scene.

``The only way we could get to the place was to listen to the cries,'' he said. The Navy later cleared a crude road to the site.

Korean Air officials took relatives of the victims in four buses to an overlook about a half-mile from the crash site, where some of them took pictures through the trees while other wept.

One woman collapsed and was taken back to the bus. A man angry at not being taken closer to the crash site screamed at Korean Air officials.

Sixty-nine bodies had been recovered from the smoldering wreckage by the time rescuers broke for the night on Wednesday. There are 29 known survivors among the 254 people on the plane.

One mystery surrounds reports of an explosion as the plane crashed.

``In my opinion it was aircraft tires that in the fire would expand and burst,'' said U.S. Navy Adm. Martin Janczak. ``I would not read anything else into that.''

The plane slammed into the ground on a hill short of the airport. Investigators will seek clues to why it did not follow a safe descent.

The airport's glide slope, which provides an electronic slanted highway to the runway, was not operating at the time.

Investigators will also ask if the crew was familiar with the airport. Korean Airlines usually uses an Airbus on the Seoul-Guam route, but switches to the larger 747 for the busier summer season.

In Seoul, airline officials insisted that the crew aboard 801 was familiar with Guam airport.

Investigators will also consider the fact that Guam is staffed by controllers hired by a private firm under contract instead of Federal Aviation Administration controllers.