A blast has torn through the Syrian town of Azaz, killing at least 43 people, according to the Syrian Observatory for Human Rights. The U.K.-based activist group says the explosion was caused by a fuel tanker rigged with a bomb, which went off outside a courthouse in the rebel-held town on Syria's border with Turkey.

Reuters reports that Turkey's state-run Andalou news service puts the death toll even higher, quoting a doctor who says at least 60 people have been killed and more than 50 have been wounded. Most of the victims of the car bomb were civilians, the Observatory says.

The Associated Press describes the scene of the explosion:

"Images shared online showed a huge plume of black smoke rising above the chaotic market and sounds of gunfire echoing in the background as onlookers gathered around the site. Bodies were strewn on the ground as a father ran away from the scene hugging his child."

No group has immediately claimed responsibility for the bombing, though the BBC reports that the Islamic State has been blamed.

The violence comes just over a week after Turkey and Russia brokered a cease-fire in the civil war-ravaged country. Since then, violence has ebbed, but rebel factions have protested what they call breaches of the agreement by the regime of Syrian President Bashar Assad. They have suspended their preparations for the peace talks planned for later this month, throwing those negotiations into doubt.

The Free Syrian Army, a rebel group backed by the Turkish government, controls Azaz, which lies less than five miles from the border. According to Al-Jazeera, the town has been racked by violence in recent months — including a November attack on rebel headquarters that killed 25 people, and another attack in October that killed at least 20 people.

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