Two U.S. service members and one American civilian were killed and three other people wounded in an ambush on Saturday by a lone member of the Islamic State group in central Syria, the U.S. military's Central Command said.

Syria's Interior Ministry spokesman Nour al-Din al-Baba said a gunman linked to the Islamic State group opened fire at the gate of a military post. He added that Syrian authorities are looking into whether the gunman was an IS member or only carried its extreme ideology. He denied reports that suggested that the attacker was a security member.

The attack on U.S. troops in Syria is the first to inflict casualties since the fall of President Bashar Assad a year ago.

Central Command said in a post on X that as a matter of respect for the families and in accordance with Department of Defense policy, the identities of the service members will be withheld until 24 hours after their next of kin have been notified.

Secretary of War Pete Hegseth posted on X: "Let it be known, if you target Americans — anywhere in the world — you will spend the rest of your brief, anxious life knowing the United States will hunt you, find you, and ruthlessly kill you."

The shooting took place near historic Palmyra, according to the state-run SANA news agency, which earlier said two members of Syria's security force and several U.S. service members had been wounded. The casualties were taken by helicopter to the al-Tanf garrison near the border with Iraq and Jordan.

The U.S. has hundreds of troops deployed in eastern Syria as part of a coalition fighting the Islamic State group.

Last month, Syria joined the international coalition fighting against the IS as Damascus improves its relations with Western countries following the ouster of Assad when insurgents captured his seat of power in Damascus.

The U.S. had no diplomatic relations with Syria under Assad, but ties have warmed since the fall of the five-decade Assad family rule. The interim president, Ahmad al-Sharaa, made a historic visit to Washington last month where he held talks with President Donald Trump.

IS was defeated on the battlefield in Syria in 2019 but the group's sleeper cells still carry out deadly attacks in the country. The United Nations says the group still has between 5,000 and 7,000 fighters in Syria and Iraq.

U.S. troops, which have maintained a presence in different parts of Syria — including Al-Tanf garrison in the central province of Homs — to train other forces as part of a broad campaign against IS, have been targeted in the past.

One of the deadliest attacks occurred in 2019 in the northern town of Manbij when a blast killed two U.S. service members and two American civilians as well as others from Syria while conducting a patrol.