"The cargo plane lost contact today (Wednesday). Now we are checking the number of crew," Barata told Xinhua via phone.

Marsudi, spokesman of the national search and rescue office, said the C208 Caravan plane was on route of Wajo and Sentani.

It departed at 2:45 p.m. local time and was scheduled to arrive at 3:24 p.m. local time, Marsudi said.

"The plane sent S.O.S. message during the flight," Marsudi said.

"Search and rescue for the plane is underway now, involving a plane and personnel from local search and rescue office. But the weather seems unfavorable," said Marsudi.