A missile strike on a commercial ship in the Gulf of Aden resulted in fatalities, marking the first confirmed deaths of crew members since Houthi militants began a wave of attacks against commercial shipping in one of the world’s busiest sea lanes.

Two people were killed and six were wounded, according to US officials. 

The True Confidence, a bulk carrier, was struck early Wednesday, according to its owners and manager, adding that they had no information about the 20 crew members. The UK said the ship has been abandoned.

The Houthis claimed responsibility for the strike, adding that a fire broke out aboard the vessel. They described the carrier as “a US ship,” which its owners said isn’t true. The ship was owned by OCM Maritime Loire LLC until Feb. 23, when it changed hands, according to the Equasis maritime database.

The attack represents the most severe human impact yet on vessels sailing through the region, including the Red Sea. Houthis have escalated their attacks on some vessels since November, in what they say is a response to the Israel-Hamas war. Many commercial vessels are avoiding the region due to the attacks and US-led strikes aimed at stopping the Houthis.

The Houthis said they will keep targeting ships linked to Israel, the US and the UK in the Red Sea and Arabian Sea until Israel’s “aggression” in Gaza stops. 

Earlier this week a missile caused a fire on a container vessel. The Houthis also recently claimed their first sinking of a ship, when the Rubymar finally became submerged after an attack in February.

The True Confidence was continuing to receive support from military forces in the region, the UK Navy said in a statement. It is owned by a company called True Confidence Shipping SA and operated by Third January Maritime Ltd., of Piraeus, Greece.

Houthi attacks have caused swaths of global shipping to avoid the region around the Red Sea, one of the world’s most important waterways for the trade of everything from oil to grain. Instead, ships are sailing thousands of miles around the coast of Africa, adding journey time and fuel costs to many goods. That in turn has left fewer ships to target in the region. 

The number of vessels arriving in the Gulf of Aden was down about 70% last week compared with the first part of December, when attacks intensified, according to Clarkson Research Services Ltd, a unit of the world’s largest shipbroker. 

The True Confidence had earlier been proceeding through the regular transit route, before suddenly turning around and drifting, ship tracking data compiled by Bloomberg show.