A car bomb ripped through a commercial area in Sadr City, a predominantly Shiite neighbourhood of Baghdad, killing at least 63 people and wounding dozens more.
Later in the day, two suicide bombers targeted police checkpoints in the northern district of Kadhimiya and in Jamia, in the west of the country, leaving a total of 29 people dead.
The market is one of the main four outdoor shopping venues in Sadr City, a sprawling slum that is home to about 2.5 million residents – almost half of Baghdad’s population of around six million.
Several victims were women inside a beauty salon, including brides who appeared to be getting ready for their weddings, police sources said. The bodies of two men believed to be grooms were found in an adjacent barber shop.
Ambulances rushed to the scene as dozens of residents walked through twisted and mangled wreckage of cars and other debris that littered the pavement, trying to help the victims.
The street was stained red with blood in many places and the facades of several buildings were heavily damaged. Smoke billowed from ground-level stores which had been gutted out by the explosion.
Karim Salih, 45, a grocer, said the bomb was inside a pick-up truck loaded with fruits and vegetables parked by a man who then disappeared among the crowds of people. Police later confirmed the statements of witnesses.
Mr Salih said: “It was such a thunderous explosion that jolted the ground.
“The force of the explosion threw me metres away and I lost consciousness for a few minutes.”
He said he suffered no injuries, but two of his workers were wounded.
In an online statement, IS said it had targeted a gathering of Shiite militia.
“Politicians are fighting each other in parliament and government while the people are being killed every day,” said Hussein Abdullah, 28, who owns an electrical appliances store. He sustained shrapnel wounds in the attack.
He added: “If they [the government] can’t protect us, then they have to let us do the job.”
Baghdad’s Sadr City is a stronghold of supporters of influential Shiite cleric Muqtada al-Sadr who have been holding protests and sit-ins for months to demand an overhaul of the political system put in place by America following the overthrow of Saddam Hussein in 2003.
Last month, hundreds of the cleric’s supporters stormed the heavily fortified Green Zone in the heart of Baghdad and broke into the parliament building.
Hours after the market attack, a suicide car bomb exploded outside a police checkpoint in Kadhimiya, a mostly Shia district that is the location of an important shrine, officials said.
Both police officers and civilians were among at least 17 people who died and 43 who were injured, officials said.
At around the same time, another suicide car bomb targeted a checkpoint in the Jamia district, which is predominantly Sunni, killing 12 people and wounding 31 more.
Delivering a speech before the United Nations Security Council last Friday, Iraq envoy Jan Kubis urged political leaders and civil society to work together to resolve the political turmoil.
IS controls significant areas in northern and western Iraq, including the country’s second-largest city of Mosul. Commercial and public places in Shiite-dominated neighbourhoods are among the most frequent targets for the Sunni militants seeking to undermine Iraqi government efforts to maintain security inside the capital.