A small island grieved over the loss of 13 residents, including members of a high school volleyball team, who were among 20 people killed in a twin-engine commuter plane crash.

A National Transportation Safety Board team left Sunday from Washington, D.C., for the island of Molokai to investigate the cause of the crash, which killed all aboard. A six-person NTSB team was expected at the site Monday.The Aloha IslandAir DH6 Twin Otter crashed into the wall of Halawa Valley on the eastern end of the island, just below the ridgeline and about 700 feet above the valley floor, Coast Guard spokesman Scott Hartvigsen said.

The cause of the crash was not known.

Rescuers recovered 20 bodies from the charred wreckage of the plane on Sunday. Fire rescue teams used helicopters to ferry the bodies back to Kahului Airport on the island of Maui, said Maui Deputy Fire Chief Leroy Hokoana said. The islands are separated by 10-mile-wide Pailolo Channel.

The victims included eight members of Molokai High School's volleyball teams, the coach of the girl's team and the school's athletic director, principal Clifford Horita said. Three other island residents also were killed.

Horita said school would be held Monday, but he planned to arrange a special morning assembly to help students cope with the tragedy.

"We'll try to help them learn how to handle this," he said.

Before the wreckage was found, about 600 of Molokai Island's 6,000 residents gathered at a community center in the town of Kaunakakai. When officials announced that the plane had crashed and there were no survivors, many wept and comforted each other.