Mostly civilians among the dead in the massive explosion, the cause of which was not immediately clear.

A powerful explosion on Wednesday in Syria‘s rebel-held northwest killed 18 people – including more than a dozen civilians – as rescuers searched for victims trapped under the rubble.

A building of at least four storeys collapsed in the town of Jisr al-Shughour in Idlib province, a region controlled by Syria’s former al-Qaeda affiliate.

A structure opposite partially caved in while surrounding buildings appeared on the verge of collapse.

A civil defence worker could be seen easing himself under a massive slab of fallen concrete to search for victims, as three colleagues crouched by his side to help.

Thirteen civilians were among those killed in the blast, the cause of which was not immediately clear, according to the Syrian Observatory for Human Rights, a Britain-based war monitor.

The explosion could have been the result of a car bomb or a vehicle carrying explosives that detonated, it said.

But bystanders and the head of the local civil defence unit, Abdelwahab al-Abdu, said they did not know what caused it.

‘People still alive’

Abu Ammar, a father of two, said he felt the “huge” blast from his home about 50 metres away.

“We ran to the place of the explosion and saw the rescue teams trying to pull out the wounded,” he said.

There were “people still alive under the rubble, and lots of body parts on the ground.”

Rescue personnel were seen directing bulldozers to clear rubble from a road.

Idlib is under the administrative control of Hay’et Tahrir al-Sham (HTS), which has renounced its ties to al-Qaeda.

The Turkestan Islamic Party, a group of foreign fighters from the ethnic Uighur Muslim minority, also has a large presence in Jisr al-Shughour.

Islamic State of Iraq and the Levant (ISIL or ISIS) has sleeper cells in the wider Idlib region.

Increasing bombardment

190323160623865

Idlib has since September been protected from a massive Syrian government offensive by a fragile ceasefire deal signed by Damascus ally Russia and rebel backer Turkey.

But the region of some three million people has come under increasing bombardment since HTS took full control in January.

On Tuesday, regime shelling killed seven civilians, including four children, in the town of Khan Sheikhoun.

Increased government artillery fire on Khan Sheikhoun has sparked one of the largest waves of displacement since the September deal.

Syria’s war has killed hundreds of thousands of people and displaced millions since the conflict began with the repression of anti-government protests in 2011.