At least 16 fishermen were feared to have been killed by pirates off the coast of southeastern Bangladesh, officials said Monday.

According to police, a fishing boat recovered three bodies with their hands and feet bound with a rope off Kutubdia Island in Cox’s Bazaar resort district. At least 13 other bodies were seen floating in the waters.

Local deputy police chief Imran Bhuiyan said pirates could be behind the deaths. The fishermen were allegedly tied up and thrown into the Bay of Bengal and left to drown.

“We believe that the pirates threw them into the sea alive,” he told AFP, adding that the bodies had no injury marks.

Other fishermen were helping police recover the bodies.

Around 23 fishermen who sailed out from Kutubdia island had gone missing a couple days before reports of the bodies surfaced, police chief of Cox’s Bazaar Mohammad Azad Mia said. He said they have no information about the other seven fishermen who are still missing.

The pirates were thought to have killed the fishermen to steal the engine, fishing nets and catch of the boat, reports AFP.

Last August, Bangladesh launched a joint air and naval operation in the Bay of Bengal after 50 fishermen were kidnapped by heavily armed pirates, GlobalPost reports.