Hundreds of civilians are fleeing two cities held by ISIS in eastern Syria after a series of deadly air strikes that killed dozens, the Syrian Observatory for Human Rights said Saturday.

The Observatory, a Britain-based monitor, said a “large-scale displacement” was underway from the cities of Albu Kamal and Mayadeen.

“Hundreds of civilians are fleeing the two cities heading towards villages in the countryside,” the monitor said.

Its director, Rami Abdel Rahman, said civilians had begun fleeing on Friday but that the displacement was continuing on Saturday morning.

He said relatives of ISIS jihadists were among those fleeing.

The two cities are in Syria’s oil-rich eastern Deir Ezzor province, which is largely under the control of the terrorist organization and regularly targeted by the US-led coalition, as well as Bashar Assad’s regime and its ally Russia.

On Friday, at least 80 relatives of ISIS jihadists were killed in US-led coalition bombing of Mayadeen, according to the Observatory.

Air raids by the coalition have pounded jihadist positions across Iraq and Syria since the group claimed responsibility for the devastating suicide bombing at a concert in the English city of Manchester on Monday.

The monitor said 33 children were among the dead in the strike on Mayadeen on Friday, the third day of heavy bombardment of the town.

According to the Observatory, 37 civilians were killed in coalition raids on the town on Thursday night, including 13 children, and another 15 were killed in coalition strikes on Wednesday.

Mayadeen has seen an influx of displaced families from ISIS-held territory in Iraq and Syria, including its bastion Raqqa.

Albu Kamal sits on the border between Iraq and Syria and has also regularly been targeted in air strikes.