A 53-year-old man competing in a Bulgarian version of reality TV show Survivor has died of a heart attack during filming at a beach resort in the central Philippines.

Moncho Vodnicharov, 53, collapsed Saturday and was attended by two doctors on the set before being rushed to hospital.

He died after completing a challenge — one of a series of activities Survivor contestants undergo to win privileges or immunity from elimination. It is not known what sort of challenge it was.

Vodnicharov was the mayor of the southern Bulgarian town of Radnevo, which has declared five days of mourning.

The Survivor franchise began in the U.S., but versions of it are being created by local networks around the world. Contestants must fend for themselves to get food, water and shelter, competing to be the sole survivor and win a large cash prize.

The resort on the Caramoan peninsula in the eastern Philippines where Bulgarian survivor was being shot is a remote and beautiful area with unusual rock formations and clear water. It has been used by Survivor crews from both France and Israel.