Yemen's Houthi rebels killed 3 mariners with an attack on a ship in the Red Sea, a European naval force says, fueling concern over a possible new wave of attacks by the Iran-backed group.

Five crew members have been rescued from a Liberian-flagged cargo ship in the Red Sea after a suspected attack from Yemen’s Houthi group, according to a maritime monitor. The attack is so far known to have killed at least three sailors out of the 22-member crew and wounded two.

A new attack targeted a ship traveling through the Red Sea on Monday after another claimed by Yemen’s Houthi rebels reportedly sunk a vessel. The private security firm Ambrey said two security guards aboard the Liberian-flagged bulk carrier had been hurt in the latest attack,