A Bell UH-1H Iroquois helicopter crashed by a residential area approximately around 10 a.m. (0100 GMT) in the eastern city of Chuncheon, about 110 kilometres (68 miles) from Seoul, reports Daily Mail.

The crew of four was rushed to hospitals. Three, except the 50-year-old pilot who is in critical condition, succumbed to their injuries, reports Yonhap News Agency.

The chopper crashed in the Gangwon Province of Chuncheon. No civilian casualties have been reported so far. The aircraft, which was completely destroyed, was on a checkout flight.

The aircraft had a flight schedule planned after the test operation," a military official said, according to the Korea Herald.

The military, the police and local fire fighters are still determining the exact cause of the crash.