At least 51 people were killed when a suicide bomber aged between 12 and 14 attacked guests dancing on the street at a wedding party in the Turkish city of Gaziantep near the Syrian border late on Saturday, the Turkish President said.
The attack was the deadliest in a series of bombings in Turkey this year, and President Tayyip Erdogan said on Sunday Islamic State was likely behind it. Turkey faces multiple security threats from militants at home and from Syria.
"Initial evidence suggests it was a Daesh attack," Erdogan said, using an Arabic name for the hardline Sunni group, during a visit to Gaziantep after the attack. He said 69 people were in hospital and 17 were "heavily injured."
Islamic State has been blamed for other attacks in Turkey, often targeting Kurdish gatherings in an effort to inflame ethnic tensions. The deadliest one was last October, when suicide bombers killed more than 100 people at a rally of pro-Kurdish and labor activists in Ankara.
Saturday's attack comes with Turkey still in shock just a month after Erdogan and the government survived an attempted coup by rogue military officers, which Ankara blames on U.S.-based Islamist preacher Fethullah Gulen. Gulen has denied the charge.
Saturday's wedding party was for a member of the pro-Kurdish Peoples' Democratic Party, it said, and the groom was among those injured. The bride was not hurt, one local official said.
Celebrations were ending at the traditional henna night party, when guests have decorative paint applied to their hands and feet. Some families had already left when the bomb went off but women and children were among the dead, witnesses said.
Blood and burns marked the walls of the narrow lane where the blast hit. Women in white and checkered scarves cried, sitting crosslegged outside the morgue waiting for word on missing relatives.
"The celebrations were coming to an end and there was a big explosion among people dancing," said 25-year-old Veli Can. "There was blood and body parts everywhere."
"We want to end these massacres," witness Ibrahim Ozdemir said. "We are in pain, especially the women and children."
NATO member Turkey is a partner in the Western coalition against Islamic State in Iraq and Syria, allowing U.S. jets to fly attacks against the group from its air bases. It has also backed some rebel groups in Syria.
Syrian rebels were preparing to launch an operation to capture a town held by Islamic State at the border with Turkey, a senior Syrian rebel said on Sunday.
Hundreds gathered for funerals on Sunday, some weeping at coffins draped in the green color of Islam, local television images showed. But other funerals would have to wait because many of the victims were blown to pieces and DNA forensics tests would be needed to identify them, security sources said.
In Gaziantep, the chief prosecutor's office said they had found a destroyed suicide vest at the blast site.
Three suspected Islamic State suicide bombers killed 44 people at Istanbul's main airport in June.
Violence has also flared again this week in the largely Kurdish southeast. Ten people were killed in bomb attacks, mostly police and soldiers, in an escalation that officials blamed the PKK.
Turkey began air strikes against Islamic State last July, in the weeks after a peace process with the PKK collapsed and it also began targeting PKK targets in northern Iraq.
Just a half an hour away from Gaziantep is the border town of Kilis which has been repeatedly hit by rockets and shelling from Islamic State territory, killing civilians on some days.
On Sunday, ruling AK Party lawmakers as well as Erdogan himself emphasized that they see Islamic State as no different to the Kurdish separatist PKK and the group led by Gulen, all three classified by Turkey as terrorist organizations.