Two military vehicles carrying Marines to the Miramar air base tumbled 100 feet off a San Diego freeway Wednesday night, killing two people and injuring as many as 20 others, the California Highway Patrol said.

The vehicles were heading to Miramar Marine Corps Air Station when they went over the side of the southbound Interstate 15 freeway at about 7:20 p.m., CHP Officer Larry Landeros said.

One of the vehicles was a tank, said Maurice Luque, spokesman for the San Diego Fire-Rescue Department. The other appeared to have been a troop carrier or truck, Landeros said.

The cause of the crash remained under investigation.

No further details were immediately available.