UPDATE: 1:00 p.m. EST -- Reports from Reuters put the current death toll from the two suicide bombings in a Sadr City market at 70, with more than 100 wounded. That would make Sunday's tragedy one of the most deadly recent attacks in Iraq; a July 2015 suicide bombing killed 120.

Original story:

The Islamic State group has claimed responsibility for a bombing in Baghdad's Sadr City. The bombings, which occurred earlier Sunday in the mostly Shiite Iraqi suburb, have killed at least 31 people, according to Reuters.

Various local news reports say there were two blasts in a market. Initial casualty reports put the deal toll at 17, with no one claiming responsibility.

This is the second ISIS-claimed attack in Baghdad in the last few days: On Thursday, two suicide bombers killed 24 people in a Shiite mosque. The Islamic State group controls a large swath of northern Iraq, laying claim to nearby Fallujah.

Islamic State militants follow a fundamentalist Sunni doctrine and consider Shiite Muslims to be "apostates," or being in violation of Muslim law. Apostasy can be punished by death.

The attacks on Iraq's capital come as the U.S. continues to increase the number of troops and private contractors hired by the Pentagon in the country and amid fears that missing radioactive material could find its way into ISIS' hands.

Increased militant activity in Libya, too, is a growing concern to Western officials, who have recently discussed the possibility of airstrikes to prevent the group from joining forces with ISIS, which controls large portions of Syria and Iraq.

While Russia and the U.S. brokered an unofficial ceasefire between Syrian forces that took effect Friday at midnight, rebel fighters claim government forces are still dropping bombs in Eastern Ghouta, outside Damascus, reported Britain's Independent. ISIS, which was not a part of the truce, has claimed responsibility for a car bombing in Damascus Saturday that killed 20 and wounded 35.