PARIS (AP) — The French Alps' high mountain police force says a small glider plane has crashed despite "excellent" weather, killing two Austrians onboard.

An official at the Hautes-Alpes gendarmes, who refused to give their name as an inquiry is ongoing, told The Associated Press on Monday the crash took place Sunday afternoon at an altitude of 2,400 meters (7,875 feet) on the mountainous Roche Rousse sector of Orcieres in the Hautes-Alpes region of southeastern France.

He said the plane suddenly lost its trajectory and crashed, instantly killing the two Austrians— the 57-year-old male pilot and a 13-year-old boy who may be his son.

The official said the circumstances of the tragedy and the identity of the victims are still unknown.

Authorities were alerted to the crash by witnesses who saw the glider fall.