Raids on Islamic State leaders have been carried out by US forces, aimed at eliminating jihadists and gathering intelligence for further operations.
Omar Abou Leila, a Syrian activist who runs the Deir Ezzor 24 group, said four helicopters landed in the village of Kumar, between the Islamic State-controlled cities of Deir al-Zour and Raqqa on Sunday 8 January. "It's an operation that apparently targeted an important figure," he told AP.
After setting up checkpoints, commandos targeted a vehicle believed to be carrying several IS fighters, killing all of them, according to CBS news.
The Syrian Observatory for Human Rights said that 25 jihadists were killed in the skirmish. However, US Navy Captain Jeff Davis reported that this figure was "greatly exaggerated".
Davis went on to say that the operation was "focused on ISIL leadership" and the troops used in the raid were from the Expeditionary Targeting Force, which has previously been deployed in Iraq.
Accounts provided to The Times by a local activist, Abdul Rahman Hasson, said two of the helicopters had remained in the air, while troops from the third aircraft attacked a number of Islamic State vehicles.
"They went down, killed some Daesh fighters and took some others. We have no confirmation of the numbers of those killed," said Ahmad Ramadan, head of the activist-run Euphrates Post group, based in Turkey.
Kubar, a village on the Euphrates River is believed to be an IS stronghold and one of Raqqa's first defensive lines. Hasson also claimed it was the location of a secret Isis prison.
A US military spokesman in Baghdad confirmed the raid but did not say which senior IS members were in their sights.
Isis chief Abu Bakr al-Baghdadi is still alive in spite of several assassination attempts, the Pentagon said. Spokesman Peter Cook told CNN that US security agencies "do think Baghdadi is alive and is still leading" the IS group.
"We are obviously doing everything we can to track his movements," he said. "If we get the opportunity, we certainly would take advantage of any opportunity to deliver him the justice he deserves," he said.
"We're doing everything we can. This is something we're spending a lot of time on."