KUALA LUMPUR, Malaysia — Two Chinese sailors have been rescued more than 50 hours after their sand dredger capsized off Malaysia’s southern coast, a maritime official said Saturday.

Three more bodies were also discovered, leaving nine others still missing.

Divers heard knocking sounds and found the two sailors in the ship’s engine room on Friday, apparently trapped in an air pocket that had kept them alive after the vessel overturned on Wednesday, said coast guard official Sanifah Yusof.

They were weak and dehydrated and have been hospitalized, he said.

Their rescue raised hopes there may be others still alive, he said, adding that air is being pumped into the ship to help possible survivors.

Sanifah said rescuers also discovered a body floating near the vessel and two more, including a woman inside the ship, on Saturday. He said this brought the death toll to four and left nine others, including a Malaysian and an Indonesian, unaccounted for.

Sanifah said a team of Chinese divers had joined the search operation and that rescue efforts had been intensified.

He said the submerged vessel was moved closer to shore and stabilized to prevent it from sinking.