Rescuers pulled six crew members alive from the Red Sea after Houthi militants attacked and sank a second ship this week, while the fate of another 15 was unknown after the Iran-aligned group said they held some of the seafarers.

Rescuers launched a search Wednesday for survivors of a Liberian-flagged cargo ship that came under attack from Yemen's Houthi rebels in the Red Sea, authorities said. At least three mariners were killed and two were wounded.