Three gunmen opened fire overnight on a coffee shop in northern Iraq where young men had gathered at the start of the weekend, leaving at least 12 people dead and 25 wounded, police and hospital sources said on Friday.

The assailants in the predominately Shi’ite town of Balad, 80 km (50 miles) north of Baghdad, armed with machine guns, shot into the crowd in the cafe from their cars for around 10 minutes before speeding off.

Once police arrived at the scene, two of the attackers detonated their suicide vests.

Four were killed and two critically wounded, medical sources added.

Within hours, ISIS posted a statement online claiming responsibility for the attack. The area, which was nearly overrun by ISIS militants in 2014, remains around 40 km from a frontline held by Shi’ite militiamen.

The attackers had passed three police checkpoints before reaching their target, said police sources who declined to be identified as they were not authorized to speak to the media.

Security forces deployed throughout the town on Friday morning, fearing more attacks.

An intelligence source said fighters from the powerful Iranian-backed Badr Organization raided a nearby house and detained 13 members of a Sunni family. There were reports of gunfire in an adjacent orchard.

The attack in Balad comes on the heels of a two-day wave of bombings in the Iraqi capital that killed nearly 100 people.

Iraqi authorities have come under heightened criticism over the security breaches.

The country is also facing a political crisis over a cabinet overhaul that has crippled government for weeks and threatens to undermine the U.S.-backed war against ISIS, which still controls swathes of territory in the north and west which it seized in 2014.