The death toll from the attack that sank the Liberian-flagged Eternity C ship is the highest from any seaborne assault carried out by the Iranian-backed rebels in the crucial maritime trade route.

Ten people have been rescued from the Red Sea after their ship sank near Yemen following an attack by the Houthis, according to the European Union’s maritime security mission, with several others believed to be being held by the rebel group.

Four seafarers were rescued in the Red Sea on Thursday two days after their cargo ship was sunk by Houthi militants, in an attack that killed at least four people. But 11 people remain missing and several others have been kidnapped following the Yemeni group’s attack on the Greek ship Eternity C.