The aircraft was caught on camera nosediving into the water while on a test flight in Thailand before reportedly being split in two upon impact.

The propeller plane appeared to be a Viking DHC-6 Twin Otter with images showing the wreckage floating on the sea in the Hua Hin district.

The plane crashed near Hua Hin Airport just after 8am.

Officials confirmed it was just over 300ft off shore at the time of the fatal plummet.

Only one passenger is said to have survived the horror smash, according to Royal Thai Police spokesperson Archayon Kraithong.

Four died upon impact with their bodies being recovered by emergency crews as a fifth was declared dead in hospital.

The condition of the survivor is still unknown.

All of those on board were police officers, Kraithong later confirmed.

The cause of the crash is still unknown with investigations ongoing.

Archayon said officials are starting to gather evidence, including black box data to help with their inquiry.

Horrified guests at the Baby Grand Hua Hin Hotel watched on as the aircraft slammed into the Gulf of Thailand.

Onlooker Isara Supasa said: “I was shocked and ran onto the beach. There was no sign of life coming from the plane.”

National Police Chief Police General Kitrat Phanphet confirmed the victim’s families will be closely supported.

Just weeks earlier, three people died after a medical helicopter carrying a patient plunged into the sea in Japan.

The coast guard deployed two planes and three ships to the area as part of the rescue operation with three survivors being found.

The pilot, Hiroshi Hamada, 66, Katsuto Yoshitake, helicopter mechanic and nurse, Sakura Kunitake, 28, were all rescued by the coast guard shortly after the crash.

The trio were found in the water clinging to inflatable lifesavers before they were rushed to hospital.