LAKE POWELL — A woman was killed and another person is missing and presumed dead after a rock slab fell on a boat.

National Park Service rangers said the incident happened Friday in Lake Canyon. Some people found a boat capsized under a small sandstone alcove.

"They had reportedly passed the vessel in the same location approximately 20 minutes earlier and had waved to the two passengers on board," said Marianne Karraker with the Glen Canyon National Recreation Area.

Rangers recovered the body of a woman and determined that a 250-foot rock slab broke off from the alcove wall and fell onto the boat, capsizing it. The other person remains missing in an area where water depths are more than 150 feet.

The names of the victims are not being released pending notification of family members, the National Park Service said.