Civilian casualties were reported after United States-led coalition forces targeted suspected al-Qaida-linked groups in the Syrian town of Atmeh near the border with Turkey, according to residents and opposition forces fighting against the Bashar Assad regime.

One resident said at least 12 people were killed in the raid that took place around midnight in a densely populated area, where tens of thousands of displaced Syrians live in makeshift camps or overcrowded housing.

The town of Atmeh is located less than a kilometer away from Turkey's border with Syria.

There were no immediate reports of any militants being killed, but residents said they heard heavy gunfire during the operation, indicating resistance to the raid.

According to the Syrian Observatory for Human Rights, there were "confirmed reports of fatalities" without providing details about their number or identities.

Residents in the area told the Agence France-Presse (AFP) they heard shelling and gunfire.

In an audio recording circulating among residents and attributed to the coalition, an Arabic speaker can be heard asking women and children to evacuate their homes in the targeted area.

The international coalition, created to fight Daesh, did not reply to an AFP request for comment about the operation.

The U.S. State Department and the spokesperson for the coalition forces in northern Syria also did not respond to requests for comment.

Charles Lister, a senior fellow with the Washington-based Middle East Institute, said he had spoken to residents who said the operation lasted more than two hours.

"Clearly they wanted whoever it was alive," Lister said.

"This looks like the biggest of this type of operation" since the Baghdadi raid, he said.

Islamic State leader Abu Bakr al-Baghdadi died in a U.S. special operations raid in northwest Syria in 2019.

Residents and opposition sources said several helicopters landed near Atmeh in the province of Idlib, the last big enclave held by the opposition forces fighting Syrian President Bashar Assad, and explosions were heard near the home of a foreign terrorist.

The terrorist who was the suspected target was with his family at the time of the raid, said an opposition official who declined to be named.

One resident said several people were killed in the raid, while another said rescuers pulled out at least 12 bodies from the rubble of a multi-story building, including children and women.

Witnesses said the raid had ended as aircraft believed to be choppers had left the site, but unidentified reconnaissance planes were still hovering in the area.

The opposition official said security from Hayat Tahrir al-Sham (HTS), the terrorist group that controls parts of northwest Syria, hurried to the location after the raid.

The northwest of Syria – Idlib province and a belt of territory around it – is mostly held by HTS, the former Nusra Front, which was part of al-Qaida until 2016.

Several foreign terrorist figures who split from the group have set up the Huras al-Din (Guardians of Religion) group, designated as a foreign terrorist organization, which has in recent years been the target of coalition strikes.

For years, the U.S. military has launched mostly drones to kill top al-Qaida operatives in northern Syria, where the militant group became active during Syria’s over decade-long civil war.

U.S.-led coalition operations against remnants of Daesh sleeper cells are more frequent in northeast Syria held by the terrorist PKK's Syrian offshoot YPG.