The accident occurred at the Syrian-Jordanian border near the settlement of At-Tanfa.
As reported by the official representative of the U.S. Central command Josh Jakes, the Pentagon did not have any information about the number of casualties as a result of the airstrike.
It is worth noting that the U.S. has previously hit the pro-government forces in Syria. For example, during Obama's presidency the Syrian army positions in Deir ez-Zor were attacked by ISIS terrorists right after the United States had launched their own airstrike. According to the US officials that attack was a mistake caused by "the human factor".
In April the U.S. Navy has already bombed Syria's Shayrat Air Base, in response allegedly to the Khan Shaykhun chemical attack.