A military helicopter crashed in South Korea on Monday, sending two people to hospital with cardiac arrest, Yonhap news agency reports.

The AH-1S helicopter crashed at around 11am local time in Gapyeong County.

Authorities said the incident was not related to a fire or explosion.

The helicopter was a Cobra AH-1S belonging to the South Korean army's 15th Aviation Group.

The helicopter was performing a routine training flight.

Both crew members were non-commissioned officers.

The cause of the crash is still unknown, and the military has launched an investigation.