TOKYO, Jan. 20 (Xinhua) -- A sightseeing helicopter carrying three people went missing near the summit of Mount Aso in Kumamoto Prefecture in southwestern Japan on Tuesday, local media reported.

The helicopter took off at 10:52 a.m. local time from the Aso Cuddly Dominion zoo in Aso City, with three people believed to be on board, including the pilot, according to public broadcaster NHK.

Around 11 a.m., an emergency call was made reporting that a smartphone's collision detection function had been activated, the report said.

Police and fire departments are searching the area near the Nakadake crater of Mt. Aso.

The helicopter was on its third sightseeing flight of the day when it went missing, and no abnormalities had been reported during the first two flights, according to the operator.

The zoo offers panoramic helicopter rides over the area, which is famed for its volcanic landscapes.