A U.S. military plane carrying five Marines crashed in southern California on Wednesday.
According to French media, there was no immediate word on the deaths.
The military has denied reports that the plane was carrying nuclear material when it crashed near Glims, just 20 miles (35 kilometers) from the Mexican border.
A spokesman told Media: “We can confirm that a 3D Marine aircraft wing crashed near Glims. There were five Navy personnel on board, and we are awaiting confirmation of the condition of all crew members.
“Contrary to social media rumors, there was no nuclear material on board,” he said.
The aircraft was identified as the MV22B Osprey. The Osprey is a so-called vertical takeoff and landing aircraft that has rotary wings that can lift it upwards to fly like a helicopter, or move it forward to give it an airplane range.
The U.S. military has suffered a series of air crashes, with four Navy soldiers killed in an air crash in Norway in March this year.