Three U.S. military personnel — two Army soldiers and a civilian interpreter — were killed on Saturday by a suspected Daesh attacker who targeted a convoy of American and Syrian forces, the U.S. military said.

Three other U.S. soldiers were wounded, the U.S. military’s Central Command said.

In a statement, Central Command said the attack by a lone gunman occurred “as the soldiers were conducting a key leader engagement” in the central Syrian town of Palmyra. “Partner forces” killed the attacker, U.S. Secretary of Defence Pete Hegseth wrote in a social media post.

Daesh did not immediately claim responsibility, but a senior U.S. official said initial assessments indicate the militant group probably carried out the attack. It took place in an area not controlled by the Syrian government, the official said.

The soldiers’ names will be withheld until 24 hours after the next-of-kin notification, the U.S. military said.

Syrian state news agency SANA quoted a security source as saying two Syrian service personnel were injured, without providing further details.

The source told SANA that American helicopters evacuated the injured to a U.S. base in Syria’s Al-Tanf region near the Iraqi border.

Tom Barrack, the U.S. ambassador to Turkey and special envoy to Syria, condemned the attack.

“We mourn the loss of three brave U.S. service members and civilian personnel and wish a speedy recovery to the Syrian troops wounded in the attack,” Barrack said in a statement.

“We remain committed to defeating terrorism with our Syrian partners.”

The attack came barely a month after Syria announced it had signed a political cooperation agreement with the U.S.-led coalition against Daesh, which coincided with Syrian President Ahmed al-Sharaa’s visit to the White House.

The coalition has carried out air strikes and ground operations in Syria targeting Daesh suspects in recent months, often with the involvement of Syria’s security forces. Syria last month also carried out a nationwide campaign arresting more than 70 people accused of links to the group.

The United States has troops stationed in northeastern Syria as part of a decade-long effort to help a Kurdish-led force there.