Two Marines have been killed in a helicopter crash on Friday at a Marine Corps base in California.

The crash, which happened at around 4:30 p.m., occurred at Twentynine Palms, a Marine Corps base located in the Mojave Desert in southern California, according to the Los Angeles Times.

Authorities have not released any names in the crash, which is still under investigation. There are no details immediately available.

A Marine official said that everyone’s “hearts go out to the family and friends of the two Marines we lost in this tragic accident.”

The crash involved the Third Marine Aircraft Wing, which was carrying two individuals when it went down at the base during a training exercise. Their names will be withheld for 24 hours pending notifications of next-of-kin.

Twentynine Palms is located in San Bernandino County in California. It is home of the Marine Corps Air Ground Combat Center Twentynine Palms, a Marine Corps base adjacent to the city. The base was formed in 1949 by nearby Marine Corps Base Camp Pendleton as the need for live-fire training grew during the outbreak of the Korean War.