STEAMBOAT SPRINGS, Colo. — Two people died Saturday when their Piper PA-28 aircraft crashed at Rabbit Ears Pass en route from Steamboat Springs to Boulder.

The victims were identified as Broomfield resident William Earl Allen, 62; and Houston resident Terry Lynn Stewart, 60. Allen was a flight instructor flying with student Stewart, the Routt County Sheriff’s Office said.

The men reportedly flew up to Steamboat Springs for lunch and crashed on the return trip.

The plane had departed Steamboat Springs and was bound for Boulder when it crashed under unknown circumstances near the top of the 9,000-foot pass, the Federal Aviation Administration said in a statement.

According to local authorities, the victims were found aboard the aircraft. They did not survive.

The circumstances of the crash were under investigation by the FAA