Updated 10:52 a.m. ET
One U.S. soldier, a Green Beret, was killed and another American was wounded in an overnight roadside bomb explosion in Manbij, Syria.
They were in a convoy. One other coalition fighter was killed in action. Five others were wounded. They were not local fighters, but part of the coalition.
Manbij had been relatively safe. ISIS was pushed out of there many months ago.
A statement from the coalition said an improvised explosive device was the cause.
The military said those wounded were evacuated for medical treatment after receiving preliminary immediate care.
The statement did not detail the nationality of the personnel involved or the location in Syria where it occurred.
"Our prayers are with their families, friends and fellow service members," coalition spokesperson Army Col. Ryan Dillon wrote on Twitter.
The Associated Press reported that "a roadside bomb exploded in the mixed Arab-Kurdish town of Manbij. Mohammed Abu Adel, the head of the Manbij Military Council, an Arab-Kurdish U.S.-backed group in the town, says the bomb went off hundreds of meters away from a security headquarters that houses the council just before midnight on Thursday."
The coalition statement says the names of those killed will be released "at the discretion of the pertinent national authorities" and it is holding off releasing more details while it investigates.
Reuters notes, "Islamic State militants continue to carry out attacks including bombings, ambushes and assassinations in Syria and Iraq despite the collapse last year of the cross-border 'caliphate' declared in 2014 by their leader, Abu Bakr al-Baghdadi."
The coalition's Combined Joint Task Force claims to have driven ISIS forces from 98 percent of the area the group once controlled.
The two deaths come two weeks after seven people died when a U.S. military helicopter crashed after hitting a power line in Iraq.