Two US soldiers and a US civilian interpreter have been killed in Syria in an ambush by an Islamic State (IS) gunman, the US Central Command (Centcom) has said.

Officials said three other service members were injured in the attack, during which the gunman was "engaged and killed". Syria's state news said two Syrian service personnel were also injured.

US President Donald Trump wrote on social media that it was "an ISIS attack" against the US and Syria and said there would be "a very serious retaliation". Syria's president sent condolences to Trump after the attack.

On Sunday, Trump said two of the injured American personnel have been released from the hospital.

The identities of those killed have yet to be released, with the military saying it is waiting until their next of kin have been informed.

In a post on X, Centcom, which directs American military operations in Europe, Africa and the Indo-Pacific, said the attack was "the result of an ambush by a lone ISIS gunman", while a Pentagon official said initial assessments showed the attack was "likely" to be carried out by the Islamic State group.

The UK-based Syrian Observatory for Human Rights said the attacker was a member of the Syrian security force.

No group has claimed responsibility for the attack, and the identity of the gunman has not been released.

The ambush occurred in Palmyra, located in the centre of the country, while the soldiers were "conducting a key leader engagement", according to Pentagon spokesperson Sean Parnell.

He added the attack is under investigation.

A Pentagon official said: "This attack took place in an area where the Syrian president does not have control."

Trump added that the three injured US soldiers were "doing well".

US Defence Secretary Pete Hegseth said: "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."

In a post on X, Syria's Foreign Minister Asaad al-Shaibani said the country condemned the attack, and extended its condolences to the families of the victims.

Tom Barrack, US ambassador to Turkey and special envoy for Syria, said: "I strongly condemn the cowardly terrorist ambush targeting a joint US–Syrian government patrol in central Syria.

"We remain committed to defeating terrorism with our Syrian partners."

Last month, President Ahmed al-Sharaa met with Donald Trump at the White House in a visit that the Syrian leader said was part of a "new era" for the two countries.

Syria recently joined an international coalition to combat IS and has pledged to co-operate with the US.

The global coalition is aimed at eliminating the remaining elements of the so-called Islamic State and stemming the flow of foreign militants to the Middle East.

In 2019, a US-backed alliance of Syrian fighters announced IS had lost the last pocket of territory in Syria it controlled, but since then the jihadist group has carried out some attacks.

The United Nations says the group still has between 5,000 and 7,000 fighters in Syria and Iraq.

US troops have maintained a presence in Syria since 2015 to help train other forces as part of a campaign against IS.