BEIRUT: U.S.-led coalition aircraft unleashed a series of airstrikes targeting the ISIS stronghold of Raqqa in what the coalition said Sunday was one of its most sustained aerial operations carried out in Syria to date. ISIS said at least 10 people were killed and many others wounded.

At least 16 airstrikes were reported late Saturday and early Sunday, triggering successive explosions that shook the city and created panic among residents, activists said. The U.S.-led coalition often targets ISIS-held towns and cities in Syria, but the overnight strikes on Raqqa were rare in their intensity.

In a statement issued early Sunday, the coalition said it had conducted 16 airstrikes throughout Raqqa, destroying vital ISIS-controlled structures and transit routes in Syria.

“The significant airstrikes tonight were executed to deny Daesh the ability to move military capabilities throughout Syria and into Iraq,” said coalition spokesman Lt. Col. Thomas Gilleran, using the Arabic acronym for the group.

“This was one of the largest deliberate engagements we have conducted to date in Syria, and it will have debilitating effects on Daesh’s ability to move” from Raqqa, he said.

Raqqa is the de facto capital of the so-called caliphate declared a year ago by ISIS in territories it controls in Iraq and Syria. The sustained airstrikes add pressure on the militants in Raqqa, still reeling from last month’s loss of the border town of Tal Abyad to Kurdish fighters. The town on the Turkish border was a major avenue for commerce and smuggling for the group.

A militant website said 10 people were killed and dozens of others wounded. An ISIS-affiliated Facebook page said one civilian was among those killed and 10 were wounded including women and children. The bombing destroyed several bridges in the area, according to both the group and anti-regime activists.

The ISIS-affiliated Aamaq news agency released a video of what it said was the effects of shelling Saturday by a U.S. drone on Raqqa. It showed several wounded men on a stretcher and at least three young boys being treated for wounds at what appeared to be a hospital.

A Raqqa-based anti-ISIS activist network reported eight civilians were killed by the coalition airstrikes, including a 10-year-old child.

The casualty figures could not be independently confirmed.

In the northeastern city of Hassakeh, ISIS suicide bombers detonated an explosives-laden truck near a main power plant Sunday. State-run news agency SANA reported casualties and damage in the plant on the southern edge of the city.

Fighting has raged in Hassakeh since ISIS attacked several southern neighborhoods held by government troops earlier this month. The violence has forced tens of thousands of residents to flee. The predominantly Kurdish city was split between government forces and Kurdish fighters, who have been fighting ISIS separately.

Meanwhile, clashes in Aleppo continued to rage between regime forces and rebel groups one day after the latter seized a large army barracks in the city’s west.

Two separate coalitions of rebel groups recently declared an offensive to seize regime-held parts of Aleppo, in some of the worst fighting since the mid-2012 clashes that ended up dividing the city.

In Damascus, rebel groups declared the launch of an offensive in the neighborhood of Jobar on the eastern outskirts of the capital, as regime airstrikes targeted the area. They posted video footage purporting to show the detonation Saturday of a soap factory being used as a regime barracks.