Eleven crew members were reported missing after their vessel, a Bangladeshi cargo ship, capsized in rough seas off Thailand.

The ship was en route to Chittagong port in Bangladesh when it met the storm in the Andaman Sea early Thursday.

The vessel went down some 32 kilometers off an island near Phuket in Thailand’s south, where waves reached five meters high, Thai officials said.

There were 17 crew members aboard the ship, according to Major Chatchai Sakdee. Five of them were rescued by a passing ship and another was pulled out of the water by a navy helicopter.

A search and rescue mission for the 11 missing is underway.

The Thai navy said the missing were in a lifeboat which was set adrift by the high seas. But fears were growing after several hours without a sighting.

Marine police Lieutenant Colonel Prasert Srikunrat said “very poor visibility” was hampering the search operations.

“We cannot find them yet after two trips by helicopters, and one by an airplane… there’s heavy rain and poor visibility,” Thammawit Marlaisukarin, a captain in the Thai navy told AFP.