A car bomb at a crowded market in northern Baghdad has killed at least 64 people and wounded 87 others, Iraqi police and medical sources say.
It happened at the Shia district of Sadr City during the morning rush hour.
The Sunni group claimed the attack, which was said to have targeted Shia militiamen.
Reports said the group, which controls swathes of northern and western Iraq, has frequently targeted Shia, whom it considers heretics.
Officials said many of the victims included women and children, while several of the injured were said to be in critical condition.
The blast damaged nearby buildings and other vehicles.