Reports are emerging of the first fatalities since Yemen’s Houthi rebels began strikes against civilian shipping in one of the world’s busiest sea lanes.

Two crew members were killed by a Houthi missile strike that hit the Barbados-flagged commercial ship, True Confidence, on Wednesday, British and U.S. officials confirmed. Four seafarers were also reported to have been severely burned and three were missing after a missile hit the ship.

The news is poised to heighten pressure on Britain and America to bolster their retaliatory strikes against the areas of Yemen controlled by the Houthis. The Iran-backed group says their attacks are to support the Palestinians in the Israel-Hamas war. “This was the sad but inevitable consequence of the Houthis recklessly firing missiles at international shipping,” the British embassy wrote in a statement on X. “They must stop.”

The Houthis said in a statement that the True Confidence’s crew had ignored warnings from Houthi naval forces before it launched the strike 50 nautical miles southwest of the Yemeni port of Aden. The ship’s Greek operators said the vessel is drifting and ablaze. Its crew of 20 and three armed guards included 15 Filipinos, four Vietnamese, two Sri Lankans, an Indian and a Nepali national.