A truck bomb at an Iraqi checkpoint south of Baghdad killed at least 60 people and wounded more than 70 on Sunday, medical and security officials said, and Islamic State claimed responsibility for the blast.

The suicide attack, involving an explosives-laden fuel tanker, is the second-deadliest this year after one on Feb. 28 that killed 78 people in Sadr City, a Shiite district of Baghdad. This was also claimed by the ultra-hardline Sunni group that controls vast swaths of territory in Iraq and in Syria.

The escalation in Islamic State bombings suggests that Iraqi government forces are being stretched thin after their recent gains against the group in the western and northern provinces.