U.S. helicopter crash near North Korean border sends 21 to hospital

A U.S. Marine CH-53E helicopter crashed just south of the demilitarized zone that separates North Korea from South Korea on Tuesday.

Military officials characterized the crash as a “hard landing,” CBS reported. All 21 on board the craft, dubbed a “Super Stallion,” were sent to the hospital for treatment. Five crew members were among the treated, CBS said.

So far, 15 have been released and those still in the hospital are in stable condition, the military told CBS.

Investigators are trying to determine the cause of the crash.

Military officials said the helicopter had been part of a U.S.-South Korean war game exercise that’s ongoing. Crew members had been flying out of their station in Okinawa, Japan, CBS reported.