A suicide bomber driving a truck packed with explosives blew himself up in a village in northern Iraq on Thursday, killing at least 15 members of the country’s Shabak minority, Reuters reported, citing police.

It was not immediately clear who was behind the attack, but Sunni Islamist militants who have a presence in Nineveh province have in the past targeted predominantly Shi’ite Shabaks living there and have warned them to leave.

The attack took place in the village of Mwafaqiya, to which Shabak families formerly living in the provincial capital Mosul had fled after being threatened.

“At 6 am this morning, a suicide truck bomber detonated himself amid the houses of my village,” said Qusay Abbas, a former Shabak representative in the Mosul provincial council. “There are still some people under the debris of their houses.”

Sunni Islamists and other insurgents including an al Qaeda affiliate have been regaining ground this year in an onslaught against Iraq’s Shi’ite-led government and its allies.

Al Qaeda views Shi’ite Muslims as non-believers.

More than 6,000 people have been killed in acts of violence across the country this year, according to monitoring group Iraq Body Count.