U.S.-led coalition forces conducted 16 airstrikes Saturday and early Sunday against key ISIS buildings and transit routes in the terror group’s stronghold of Raqqa, Syria, a U.S. Army official said.

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.

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

Gilleran, the spokesperson for the Combined Joint Task Force’s Operation Inherent Resolve, also called it one of the “largest deliberate engagements” executed in Syria to-date.

“It will have debilitating effects on [ISIS’s] ability to move from Raqqa,” he said.

Raqqa is the de facto capital of the so-called Islamic caliphate declared a year ago by the Islamic State group in territories it controls in Iraq and Syria.

An ISIS-affiliated militant website confirmed the strikes on the center of the city, saying 10 people were killed and dozens wounded. It also published purported photos of dead victims, including two of young boys suggesting they were civilians.

A Raqqa-based anti-ISIS activist network reported eight civilians were killed by the coalition airstrikes, including a 10-year-old child. The report could not be independently confirmed.

The network, called Raqqa is Being Silently Slaughtered, said at least one airstrike targeted a group of ISIS members in the city center. Another targeted an ISIS checkpoint while a third destroyed large parts of an ISIS-held brick factory in the city.

The coalition regularly targets the Islamic State group, which controls about a third of Iraq and Syria.

In the remote 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 the IS group separately.

In Iraq, a Defense Ministry statement said government forces repelled an ISIS attack Sunday morning on the town of Haditha and the nearby Haditha dam in Anbar province. At least 20 militants were killed in the failed attack, said the statement, which did not provide any further information.

Iraqi forces, backed by Shiite militias, have been struggling to recapture areas lost to ISIS in the country's west and north.

In May, the militant group scored a stunning victory, overrunning Ramadi, the provincial capital of western Anbar province. Yet, Haditha and some other towns remain under control of government forces and allied Sunni tribal fighters.

In Lebanon, some 200 Kurdish nationals staged a demonstration in downtown Beirut in solidarity with their brethren in Syria who are fighting against ISIS militants.

Fox News’ Jennifer Griffin contributed to this report.