Syrian Kurdish forces regained full control of Tal Abyad on Wednesday, expelling Islamic state of Iraq and Syria (ISIS) group fighters who had seized a district of the strategic border town, a monitor said.

“Kurdish fighters expelled ISIS from the Mashur Al-Fawqani district that they had captured yesterday (Tuesday),” said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

He said at least three fighters of the Kurdish People’s Protection Units (YPG) and four ISIS terrorists were killed in clashes on Wednesday.

YPG spokesman Redur Khalil confirmed that the town had been secured.

“The Daesh group that entered the Mashur Al-Fawqani district... was eliminated completely and expelled from the area,” he told AFP.

He said three ISIS fighters had been killed in the fighting, and a fourth died detonating an explosive belt.

Tal Abyad, on the border with Turkey, was formerly an ISIS stronghold, which served as a key conduit for the group to bring in weapons and fighters, and export black market oil.

But just over two weeks ago, Kurdish forces, backed by Syrian rebel allies and U.S.-led air strikes, seized the town from the extremist group.

ISIS forces launched a surprise attack against the town on Tuesday, overrunning the Mashur Al-Fawqani district in heavy fighting.

But by late Wednesday morning, the town was back under full Kurdish control, the Observatory said.