The pilot and four passengers on a helicopter tour of the Hoover Dam and Lake Mead were killed in a crash on Wednesday in Nevada, a spokesman for the National Park Service said.

A National Park Service search team, which found the crash site by helicopter Wednesday night, said there were no survivors. The team could not remove the bodies until daybreak on Thursday, however.

The air tour, operated by Sundance Tours, originated from Las Vegas just before 5 p.m. and crashed somewhere in the River Mountains shortly after takeoff.

The Federal Aviation Administration is conducting an investigation into the cause of the crash.