More than 100 others were wounded in the attack
At least 41 people have been killed by a suicide bomber who blew himself as trophies were presented after a local football tournament in Iraq.
Seventeen of the dead were said to be boys aged between 10 and 16.
More than 100 others were wounded in the attack near the village of al Asriya, 25 miles (40km) south of Baghdad.
Video posted on social media shows a local official speaking in front of a table covered with trophies and calling out the name of a player before a huge explosion.
The footage cuts off with a yellow flash of light before resuming with the chaotic scenes afterwards.
Mayor Ahmed Shaker was among the dead, along with one of his bodyguards and at least five members of the security forces.
"The suicide bomber cut through the crowd to approach the centre of the gathering and blew himself up as the mayor was presenting awards," an 18-year-old witness told AFP.
Islamic State said it carried out the attack, which it claimed was targeting Shia militiamen.
It also said it killed three Iraqi soldiers in an attack on a military base in Anbar province.
"Four suicide bombers this morning infiltrated the military base of Al Asad on its northern edge," said Major General Ali Ibrahim Daboun, head of the Al Jazeera Operations Command.
IS has lost ground in recent months in Iraq and Syria and but has hit back with a series of attacks, including the Brussels bombings.
On Friday, the US said the group's second-in-command had been killed in an American raid in Syria.
Defence Secretary Ash Carter told reporters the "well-known terrorist", Haji Imam, also known as Abdul Rahman Mustafa al Qaduli, was the group's finance minister.
In Iraq, a military spokesman announced the country's troops and Sunni tribal fighters had recaptured the town of Kubeisa in Anbar from IS.
The day before IS fighters were pushed out of a string of villages in Iraq's northern Nineveh province as the US-led military coalition carried out airstrikes.
Iraqi ground forces are working to build on recent gains in Anbar and prepare for an eventual push on Mosul, the largest city held by the militants in their self-declared "caliphate" in northern Iraq and Syria.
The US estimates IS has lost 40% of the territory it once held in Iraq, as well as around 20% of its territory in Syria.