by Sarah See
A pilot and four passengers on a tour of the Las Vegas Strip and Hoover Dam were killed Wednesday evening in a helicopter crash, according to federal authorities.
The aircraft slammed into a mountainside about 4.5 miles west of Southern Nevada Water Authority around 5 p.m., National Park Service spokesman Andrew Munoz said.
Numerous witnesses heard the crash and reported seeing smoke near the edge of Lake Mead, Munoz said.
Recovery and investigative teams headed to the scene, a remote site in the River Mountains of Lake Mead Recreational Park, about 30 miles east from the Las Vegas Strip, according to CNN and the Associated Press.
The initial rescue was slowed and later delayed by officials until early Thursday, due to inaccessibility to the area by road, according to the Associated Press.
All five people on board were confirmed dead by the Las Vegas police search and rescue team, which reached the scene by helicopter, Munoz said.
No information about the victims' identities was released by authorities, according to the Associated Press.
The Sundance Helicopters aircraft crashed under unknown circumstances, Federal Aviation Administration spokesman Ian Gregor said to CNN.
There were no notable weather conditions that might have caused the accident, Munoz said.
A 12-member team will investigate the crash, according to the National Transportation Board.
Sundance Helicopters has been in business since 1985 and has had previous accidents, according to state records.