(AP) — A helicopter crashed in western Colorado Monday, killing all three people aboard, authorities said.

Garfield County Sheriff’s Deputy Ward Stowe said his office could not immediately release the names of those killed in the crash near Silt. Witnesses who saw the crash believe the helicopter was carrying a crew inspecting power lines, and that the helicopter snagged a line, Stowe said.

Stowe said the helicopter bore no identifying marks, so it wasn’t immediately clear who owned it or who might have been operating it.

Federal Aviation Administration spokesman Allen Kenitzer said that according to preliminary information, the helicopter was being used by a power company for survey work and struck power lines before the crash.

Kenitzer said the FAA and the National Transportation Safety Board were investigating.