The Indian air force Friday lost contact with a transport plane carrying 29 people to islands in the Bay of Bengal, the defense ministry said.

The AN-32 aircraft took off from the southern city of Chennai at 8.30 a.m. and was flying over the bay to the city of Port Blair in the Andaman and Nicobar islands, said Nitin Wakanker a spokesman for India’s defense ministry.

The flight was supposed to last three hours but there was no contact for nearly three hours beyond its arrival time. Wakanker said the Russian-made aircraft could go for four hours without refueling.

A massive search by the air force, navy and coast guard has been launched, Wakanker added.

No other details were immediately available.