A U.S. Marine transport aircraft carrying five Marines went down Wednesday afternoon in a remote part of Southern California.

The MV-22 Osprey, belonging to the 3rd Marine Aircraft Wing, went down in a desert area near Glamis, California, Maj. Mason Englehart confirmed to CBS News. The crash occurred at around 12:25 p.m. local time.

The aircraft was carrying five Marines, Englehart said, but he could not immediately confirm the total number of people aboard, including the crew, or whether there were fatalities or injuries.

Installation Federal Fire and Imperial County Fire Department responded to the crash, Naval Air Facility El Centro said, adding that “contrary to initial reports, there was no nuclear material on board the aircraft.”  

Glamis is located in rural Imperial County, about 50 miles north of the U.S.-Mexico border.

The 3rd Marine Aircraft Wing is based out of Marine Corps Air Station Miramar, while the Osprey itself was based out of Marine Corps Air Station Camp Pendleton, Englehart said. Both are in neighboring San Diego County. 

The cause of the crash was not clear.

The Osprey is a tiltrotor aircraft used to move troops and supplies, according to the Marines. It can take off and land like a helicopter, but can also fly like a plane.