The search for those missing after Yemen’s Houthi rebels sank a ship in the Red Sea has ended as at least four people are presumed dead and 11 others remain unaccounted for, the private security firms involved say.

The announcement comes as satellite photos show long, trailing oil slicks from where the bulk carrier Eternity C sank, as well as another where the sinking of the bulk carrier Magic Seas by the Iranian-backed Houthis took place.

Both ships were attacked over a week ago by the rebels as part of their campaign targeting vessels over the Israel-Hamas war in the Gaza Strip that’s upended shipping in the Red Sea, through which $1 trillion of goods usually passes a year.

The private security firms Ambrey and Diaplous Group ran the search for those missing from the Eternity C, which had a three-man security team aboard but requested no escort from either the US Navy or a European Union force in the region. The ship came under attack July 7 and faced hours of Houthi assaults by small arms and bomb-carrying drones before ultimately sinking in the Red Sea.

Ten people were recovered alive from the attack, including eight Filipino crew members and a Greek and Indian from the vessel’s security team, the EU’s Operation Aspides said. At least four are presumed to have been killed in the attack, leaving 11 others missing, the EU mission has said.

The Houthis claimed to have taken some mariners after the attack, but have offered no evidence of that. The US Embassy in Yemen said it believed the rebels had “kidnapped” some of the crew.