BEIRUT (AP) — Imprisoned Islamic State militants broke out into riots again on Monday at a jail in northeastern Syria, hours after the Kurdish-led forces running the site said it had restored order, activists said.

Gunfire could be heard in the area as ambulances rushed the wounded from inside the prison to hospitals and clinics in the nearby city of Hassakeh, activists on the ground said. U.S.-led forces flew overhead dropping light bombs illuminate the area for the Kurdish forces while drones hovered over the facility, they added.

The prison riots first broke out Sunday night when former Islamic State members held there began knocking down doors and digging holes in walls between cells. It was one of the most serious uprisings by the prisoners since the Islamic State's defeat a year ago.

Earlier on Monday, Kino Gabriel, a spokesman for the Kurdish-led Syrian Democratic Forces, said the situation in the prison in Hassakeh was "fully under control." He said their anti-terrorism force "ended the riots and secured the facility and all prisoners inside."

It was not immediately clear if the riots were triggered by concerns over the spread of the new coronavirus.

Mustafa Bali, another spokesman for the forces, said late Sunday that so far there is no connection between the riot and fears of the fast-spreading virus. So far there are no official reports of infection in Kurdish-administered northeastern Syria or in any detention facilities there.

Gabriel did not say earlier whether there were casualties in the operation to re-secure the prison adding that none of the prisoners were able to escape.

Kurdish authorities run more than two dozen detention facilities, scattered around northeastern Syria, holding about 10,000 IS fighters. Among the detainees are some 2,000 foreigners, including about 800 Europeans.

The Kurdish-led forces, backed by the U.S-led coalition, declared a military victory against IS in March last year, after seizing control of the last sliver of land the militants had controlled in southeast Syria.

Adnan Hassan, a citizen journalist near the camp, told The Associated Press that gunfire could be heard inside the prison adding that ambulances are evacuating the wounded from both sides. He added that a huge SDF force arrived in the area before sunset and cordoned the area around the prison.

The Rojava Information Center, an activist collective in the Kurdish-held areas, also reported gunfire and ambulances entering the prison. It added that SDF General Commander Mazloum Abdi arrived at the scene.

Earlier Monday, a third spokesman for the forces, told the AP that IS militants were still rioting on one of the floors of the prison. Mervan Qamishlo said in a voice message from the area that IS “members are still out of control on one of the floors.”

Hassan said IS members are rioting on the ground floor while the first and second floors are controlled by Kurdish fighters.

North Press Agency, a media platform operating in the Kurdish-administered areas, and the Britain-based Syrian Observatory for Human Rights, an opposition war monitor, said Monday that the local police force, known as Asayesh, had detained four IS members who were able to flee the night before.

The prison is believed to house foreign IS militants. It is not clear what nationalities were held there.

A video posted by activists said to be taken during Sunday's riots, showed two inmates carrying a banner with writing in Arabic that reads: “We call upon the coalition and international organizations that human rights be respected.”

The U.S-led coalition said it was assisting the SDF with aerial surveillance as they quell the riot. The coalition said in a tweet that the facility holds low level IS members. The coalition said its forces don't staff any detention facilities in Syria.

The Rojava Information Center said the prison in Hassakeh's southern neighborhood of Ghoeiran houses some 1,000 low-level foreign IS members. It added that the upper levels of the prison hold mostly Syrian IS members.

Bali said late Sunday that the rioters were in full control of the ground floor of the prison and have smashed and removed the prison's internal doors.

The Kurdish authorities have asked countries to repatriate their nationals, saying keeping thousands of detainees in crammed facilities is putting a strain on their forces.

“These incidents confirm that Syrian Democratic Forces are able to secure Daesh terrorists,” Gabriel said using an Arabic acronym to refer to IS. He added that the incidents also show that the international community should help the SDF to “fully secure” detention facilities and camps hosting families of IS militants.

The families of IS militants and supporters who came out of the last territory controlled by the group are also holed in camps around the Kurdish-controlled areas — the largest one housing nearly 70,000 women and children, many of them foreigners.