Updated

Two generals who led the helicopter unit of Cambodia's air force were killed in a crash Monday, along with two pilots, police said. Defense Minister Tea Banh, who rushed to the crash site in a muddy pond south of the capital, said a fifth person on the chopper was seriously injured.

Gen. Um Phy, deputy chief of staff of Cambodia's air force, confirmed the casualty count and said the aircraft was a Chinese-made Z-9 helicopter. Authorities had previously said five people were killed.

It was not immediately clear what caused the accident, which police said was a training mission for new pilots. More than six hours after the morning crash, only two bodies had been recovered, and divers were still looking for the other two.

Two of the dead men were a major general and a brigadier general, Phnom Penh Deputy Police Chief Chuon Narin said. An incident report filed by police at the scene said the generals were the commander and deputy commander of the helicopter unit, and the other two men were pilots. Military officials confirmed the men's ranks, but not their positions. The survivor was not identified.

The chopper went down about 10 kilometers (6 miles) south of Phnom Penh, sinking in a muddy pond surrounded by rural land and rice fields.

Defense Ministry Secretary of State Moeung Samphan said 300 military personnel were sent to take part in the recovery operation.

Chhay Bunna, chief of police at Phnom Penh's nearby international airport, said the flight was a training mission for new pilots. Tea Banh said the area where the crash took place has been used for training for several years without any previous accidents.

A witness said she saw helicopters flying the same route almost every day, but the doomed flight seemed to be flying lower than usual, almost hitting her house.

Ath Neang, 48, who lives about 15 meters (yards) from the pond, said that as one of the craft's rotor blades hit the bank of the pond, one man jumped out into the water. At about the same time, she heard what sounded like an explosion from the aircraft, which then sank.