Rescuers pulled six crew members alive from the Red Sea on Wednesday and were searching for 15 still missing from the second of two freighters sunk in as many days by suspected Houthi attackers.
Four of the 25 people aboard the Eternity C cargo ship were killed before the rest of the crew abandoned the vessel, which sank on Wednesday morning after being attacked on Monday and Tuesday, sources at security companies involved in a rescue operation said.
The six seafarers who were rescued had spent more than 24 hours in the water, they said. One source had said earlier that seven people had been rescued but the EU's Aspides naval mission, which protects Red Sea shipping, issued a statement confirming that just six had been pulled from the sea.
The Houthis claimed responsibility for a similar attack on Sunday targeting another ship, the Magic Seas. All crew from the Magic Seas were rescued before it sank.
"We will continue to search for the remaining crew until the last light," said an official at Greece-based maritime risk management firm Diaplous.
"We aim at a peaceful operation," the official said earlier.
Both of the ships that were attacked flew Liberia flags and were operated by Greek firms.
Eternity C was first attacked on Monday afternoon with sea drones and rocket-propelled grenades fired from speed boats by suspected Yemen-based Houthi militants, maritime security sources said. Lifeboats were destroyed during the raid. By Tuesday morning the vessel was adrift and listing.
Two security sources told Reuters on Wednesday that the vessel was hit again with sea drones on Tuesday, forcing the crew and armed guards to abandon it for the sea. The Houthis stayed with the vessel until the early hours of Wednesday, one of the sources said.
There were fears that some of the crew who jumped into the water may have been kidnapped by Houthis, the source added, according to Reuters. Skiffs were in the area as the rescue efforts were under way.
The crew comprised 21 Filipinos and one Russian. Three armed guards were also on board, including one Greek and one Indian, who was one of those rescued.