The United States has carried out previous raids in Syria against ISIS militants, but Thursday’s would be the first known operation in a zone held by forces loyal to President Bashar al-Assad.

Early on Thursday, US special forces carried out a rare operation on the government-held village of Muluk Saray in the northeastern province of Hasakah, Syrian state television said in its Telegram channel.

It said one person was killed and others were captured. It gave no further details on their identities.

US Central Command (CENTCOM) Spokesman Col. Joseph Buccino told Reuters that the US forces conducted a “raid” overnight Wednesday, targeting a “senior ISIS official.”

Buccino added that more information would be released once operational details were confirmed.

Two security sources told Reuters that the man who was killed was an ISIS official wanted by the United States.

“The airborne operation targeted a key ISIS leader present in the areas controlled by the Syrian government. It was successful,” one of the security sources said.

The source said the slain man was responsible for coordinating across ISIS sleeper cells in the area.

“This operation aims to expand the scope of targeting this organization’s members across different parts of Syria,” the source added.

The second source confirmed the man killed was an ISIS official and said the US forces had taken his body with them as they retreated.

A local source said the man had moved to Muluk Saray village in recent years from Taif, a town near the border with Iraq that was once an ISIS stronghold.

“People thought he was a shepherd - no one knows his true identity,” said the source.

The local source said US forces also raided a building used by Syrian security and detained “several people” there.

Other residents of the area confirmed the raid to Reuters.

One said that US helicopters landed in the village after midnight and told residents by loudspeaker to stay indoors and keep their lights off.

The resident said the operation lasted several hours and that there was no exchange of fire with the US troops.

Citing reliable sources, the London-based Syrian Observatory for Human Rights also said one unidentified man was killed during a US airdrop near the village of Moluk Sarray.

It stated that the person killed in the operation was “an Iraqi national and likely a senior ISIS member who was killed after refusing to surrender to US forces.”

The war monitor reported that two families along with the head of a local security headquarters were arrested during the operation, which was said to have taken place about 17-km south of Qamishli city.