The Islamic State group has claimed responsibility for an overnight suicide attack in Baghdad that left 17 people dead and 48 wounded.

The Site Intelligence group, which monitors extremist groups, reported the claim on Thursday in which the IS group warns Iraqi Shias that the “flame of the battle” in Mosul will come to them in Baghdad, Karbala, and Najaf.

On Wednesday night, a suicide truck bomb targeted a police checkpoint on Baghdad’s main southern entrance. Three policemen were among the dead while the rest were civilians, police and health officials said on condition of anonymity under regulations.

The attack came as U.S.-backed forces are launching fierce fighting in western Mosul. After the beginning the operation to retake Mosul in October, Iraqi authorities in January declared they have liberated eastern Mosul.