BEIRUT — An explosion in northern Syria collapsed two five-story buildings Sunday, killing at least 36 people and wounding many others, opposition activists said.
The opposition-run Syrian Civil Defense, first responders also known as the White Helmets, said the blast occurred in the village of Sarmada near the Turkish border. Many of the victims were buried in the rubble of the buildings, it said.
Officials said the cause of the explosion has not been determined, but the Britain-based Syrian Observatory for Human Rights said an arms depot in the complex had detonated.
The Observatory put the death toll at 39, including 21 women and children.
An opposition media group known as the Smart news agency, said the dead included civilians as well as members of the Al Qaeda-linked Levant Liberation Committee.
The Observatory said the arms depot that detonated was in the basement of one of the buildings. It said the depot was run by an arms dealer close to the Levant Liberation Committee.
In a separate development, Syrian government forces fighting rebels in Idlib province have sent more reinforcements before a potential offensive on the last major rebel stronghold in Syria.
The progovernment newspaper Al-Watan said Sunday that many military reinforcements have reached the outskirts of Idlib province as a preliminary step to launch a wide-scale offensive.
Quoting military sources, the paper said that troops have reached the northern countryside of the neighboring Hama province as part of military preparations to recapture Idlib province.
The expected offensive on Idlib comes after government forces captured major rebel strongholds earlier this year near the capital Damascus and in the southern provinces of Daraa and Quneitra.
The paper said the battle would be ‘‘comprehensive’’ starting from Hama’s northern countryside to the southern countryside of Aleppo, adding that the target of the battle is to seize Idlib City.
Government airstrikes on the province on Friday killed dozens.
Progovernment activists said on social media that the elite Tiger Force, led by Brigadier General Suheil al-Hassan, arrived in northern Syria to spearhead what they called the ‘‘Dawn of Idlib’’ operation.
The UN’s children’s agency warned last week that the battle between government forces and rebels for Idlib province could affect the lives of more than 1 million children.
Food, water, and medicine are already in short supply in the largely rural province, which is now home to over 1 million Syrians displaced from their homes by government offensives in other parts of the country, UNICEF said.
The agency said the battle for Idlib would exacerbate an already dire humanitarian situation there and potentially displace 350,000 children.
Syria’s government dropped leaflets across the province on Thursday, urging residents to reconcile with its rule. Officials have warned that government forces will take back the province by force if necessary.
