A car bombing targeted US forces in northeast Syria on Monday, in the second such attack on American personnel in the country in less than a week.
A spokesman for the US-led coalition said that no American troops were killed in the blast which targeted "a combined US and Syrian partner force convoy."
ISIS released a statement on its Aamaq news agency claiming responsibility for the blast which it says targeted US troops and US-backed Kurdish forces near a checkpoint south of the town of Al Shadadeh.
Al Shadadeh lies to the south of Hasakeh, capital of the eponymous province, which has been relatively spared by the war that erupted in Syria nearly eight years ago.
Aamaq said a suicide car bomb was behind the blast.
The UK-based Syrian Observatory for Human Rights said five members of the Washington-backed Syrian Democratic Forces were killed in the blast. The war monitor said two American soldiers were also wounded.
The SDF did not confirm the toll. The group was also not immediately available for comment.
The Kurdish-run Hawar news agency said that three people were wounded in the attack, including two SDF members and one American soldier.
Hawar did not report any casualties.
A video published by Hawar purported to show plumes of smoke rising from the site of the blast.
Last week, an ISIS attack on US forces in Manbij, killed four American personnel, including two US service members, one Department of Defence (DoD) civilian and one contractor supporting DoD.
It marked the largest loss of US life in Syria since Washington entered the conflict
Last month Donald Trump announced the US was withdrawing troops out of Syria, declaring ISIS defeated.
But the US President's move shocked US military officials and local partners who were not consulted on the withdrawal.
Editorial: Attack demonstrates enduring ISIS threat