On Sunday morning, Dec. 31, at 6:30am (local time) the container ship Maersk Hangzhou issued a second distress call in less than 24 hours reporting being under attack by four Iranian-backed Houthi small boats. The boats, originating from Houthi-controlled areas in Yemen, fired at the container ship, getting to within 20 meters of the ship, and attempted to board.

As the ship’s security forces attempted to hold the attackers at bay, helicopters from the USS Eisenhower carrier group arrived and the Houthis opened fire on them.

“The small boats fired upon the US helicopters with crew-served weapons and small arms,” Central Command said in a statement. “The US Navy helicopters returned fire in self-defense, sinking three of the four small boats, and killing the crews. The fourth boat fled the area. There was no damage to U.S. personnel or equipment.” Central Command did not say how many had been killed, but in a statement later on Sunday the Houthis said that 10 of their fighters were dead.

The New York Times notes that It appeared to be the first time that American and allied forces patrolling the Red Sea, a critical waterway for oil and other shipments, have engaged in a deadly firefight with the Houthis since their attacks on ships began in October, following the outbreak of the war between Israel and Hamas.

The Maersk Hangzhou had previously been struck by a Houthi missile at around 1730 GMT on Saturday, 55 nautical miles southwest of Al Hodeidah, Yemen. Maersk announced it would delay all transits through the area for 48 hours.

Following Saturday’s missile attack, the ship is said to be “seaworthy” with no reported injuries. The destroyers USS Gravely and USS Laboon responded to the incident, with the USS Gravely successfully shooting down two anti-ship ballistic missiles fired from Houthi-controlled areas in Yemen.

On Dec. 26, the USS Laboon and F/A-18 Super Hornets from the USS Eisenhower carrier strike group shot down “twelve one-way attack drones, three anti-ship ballistic missiles, and two land attack cruise missiles in the Southern Red Sea that were fired by the Houthis over a 10-hour period,” the command said.

Thanks to Alaric Bond for contributing to this post.