Residents gather at the site of a bomb attack in Syria’s northeastern city of Qamishli. (Delil Souleiman/AFP via Getty Images)

A suicide bomber in an empty livestock truck laden with explosives struck Wednesday in a crowded district in the predominantly Kurdish town of Qamishli in northern Syria, causing massive destruction and killing 44 people in an attack claimed by the Islamic State militant group.

Residents and activists described a huge explosion in the western district of the town the Kurds call the capital of their self-declared autonomous enclave in northern Syria.

Most of the victims were civilians who were lingering in the district that also houses a station for the Kurdish security forces. It was not clear whether any Kurdish fighters were among those killed.

Qamishli, near the Turkish border, is mainly controlled by Kurds, but Syrian government forces are present and control the town’s airport.

The Kurds, Syria’s largest ethnic minority, have carved out a semi-autonomous enclave in Syria’s north since the start of the conflict in 2011.

Separately, the official Syrian Arab News Agency reported a total blackout in nearby Aleppo province, accusing rebel groups of hitting the main power station in the provincial and deeply divided capital. Government forces and allied troops have tightened the noose on the main rebel enclave in the city of Aleppo, urging fighters there to surrender. Humanitarian groups have warned of a major catastrophe if the siege on the rebel-held parts of Aleppo continued.

Kurdish officials said Islamic State militants targeted Qamishli in retaliation for the ongoing offensive against Manbij, an Islamic State stronghold east of Qamishli.

The predominantly Kurdish Syria Democratic Forces, backed by airstrikes and training from a U.S.-led coalition, have been the main force fighting the Islamic State on the ground in northern Syria. Kurdish forces have also been the most successful ground force in terms of reclaiming territory and towns from the Islamic State over the past two years.

In a statement published by the Islamic State-linked Aamaq news agency, the group said it carried out the attack in Qamishli. In a later statement, it said the suicide bombing was in retaliation for the U.S.-led airstrikes in Manbij, threatening the Kurds specifically with more attacks.