BAGHDAD -- Two suicide bombers killed more than two dozen people in Baghdad on Monday, mostly street vendors and day laborers gathered at dawn in hopes of finding work at an open-air market, in the first major attack in the Iraqi capital since the government declared victory over the Islamic State.
The carnage in Tayaran Square punctured a growing sense of hope and pride that had permeated Baghdad after Iraq's security forces, bolstered by large numbers of volunteers and fresh recruits, successfully fought grueling battles against the insurgent group that had held one-third of Iraqi territory and terrorized millions of citizens.
There was no immediate claim of responsibility for the bombings, but officials in charge of security in the capital immediately cast suspicion on Islamic State sleeper cells, the target of Iraq's intelligence and counterterrorism forces since major military operations ended in the fall.
Even as battles against Islamic State militants raged in northern Iraq and in its second-largest city, Mosul, Baghdad had largely been free of violence. The suicide bombings Monday morning caught many residents of the capital off guard, as they had become used to living relatively free of fear, taking their families to parks and shopping malls.
The attacks came a day after Prime Minister Haider al-Abadi and other politicians announced competing coalitions ahead of national elections scheduled for May. Since the overthrow of Saddam Hussein in 2003, campaign seasons in Iraq have been scarred by terrorist attacks and other violence.
It was still unclear how the two assailants wearing suicide vests had entered Baghdad or why they had chosen to attack a market popular for cheap electronics and secondhand clothes.
The first assailant detonated his explosives around 6 a.m., as the sun was rising and as day laborers, shopkeepers and street vendors were starting to gather for work, according to Maj. Muhammad Mudhir, a traffic police officer who witnessed the attack. Minutes later, as people rushed to help the wounded, the second assailant detonated his explosives, said Kadhim Ali, a construction worker who was at the square.
Dr. Abdul Ghani, the director of Al Rusafa hospital in Baghdad, said at least 27 people had been killed, and 60 others wounded, many of whom were in a serious condition.
Since counterterrorism operations were ramped up in 2015, Iraqi security forces have established a tight security cordon around Baghdad in an attempt to keep insurgents and violence from infiltrating the city.
The belt of suburbs and farms to the west of the capital have long been home to bomb factories for Al Qaeda offshoots that have plagued Iraq since the mid-2000s.
Muhammad al-Jiwebrawi, the head of the Baghdad Province's security committee, said those areas around the capital remained insecure. He urged the government to increase intelligence operations around the city.
"Islamic State terrorists are still present," Mr. Jiwebrawi said. "There are reasons for what they are doing."
Although the areas around the capital have been relatively safe compared with previous years, violence has not disappeared.
On Jan. 13, an insurgent detonated an explosive vest near a convoy carrying the head of Baghdad's provincial government, wounding four Iraqi security forces.
A suicide bombing on a checkpoint in the north of the city on Saturday killed at least five people, according to the Iraqi police.