According to CNN, two US military officials were quoted as saying the incident happened on Tuesday.
A military official with the US-led coalition fighting ISIS told CNN that
"A convoy of about 10 vehicles was passing through the northern portion of the 55km 'de-confliction' zone surrounding the coalition base in At Tanf, Syria, a buffer area that was negotiated by Russia and the US-led coalition. US-backed local Maghawir Al-Thawra fighters accompanied by US advisors moved to intercept the convoy and identify it. When they discovered that the convoy included IS fighters, an intense firefight broke out with about 15 IS fighters killed in the initial battle. No coalition forces were killed or wounded," the official said.
The US-led coalition, Operation Inherent Resolve, issued a statement later on Thursday saying over 20 ISIS fighters were killed in the battle. The two US military officials, however, told CNN the number was 21 killed and 17 captured.
Those captured included several foreign fighters from other countries in the Middle East.
Over 50 foreign IS fighters have been captured in Syria and Iraq since November. (ANI)