Masked gunmen armed with assault rifles and grenades have attacked a wedding party in the country's Kurdish southeast, killing at least 45 people including many women and children.
The attack was one of the worst involving civilians in Turkey's modern history.
Besir Atalay, the interior minister, said it was most likely the result of a blood feud between families.
Eight people have been arrested over the killings.
Ahmet Ferhat Ozen, the deputy governor of the province of Mardin, said the assailants stormed a house in Bilge village near Sultankoy, 12 miles from Mardin, hurling grenades and opening fire on wedding guests.
"There were a few people, they broke into the house and started spraying the place with bullets, hitting both men and women, their faces were covered with masks," said a 20-year-old female witness, who declined to be named.
She said there were about 200 people at the wedding party. Most of the dead are believed to be women and children.
Some of the assailants escaped from the isolated region of Turkey on the border with Syria before soldiers surrounded the village and cut off road access. Pursuit of the attackers was being hindered by a sandstorm, authorities said.
Local media said the families of both the bride and the groom included members of the Village Guard, a heavily armed state-backed militia set up to combat Kurdish separatist guerrillas and provide intelligence in southeast Turkey.
The fate of the bride and the groom was unknown.
State-run news agency Anatolian reported the daughter of the village chief, called a muhtar, was being married when the attack, which lasted 15 minutes, took place.
Mr Atalay did not mention the PKK, who seek an ethnic Kurdish homeland in the southeast, but indicated his remarks meant they were not involved.
"Evidence so far shows it was not the work of a terrorist group, but the prosecutor is working on the case and should have a clearer idea soon of what happened," he told reporters when asked it the PKK was behind the attack.
Mr Atalay briefed Prime Minister Tayyip Erdogan on the attack. He said 45 people had died and six more people were injured.
The village head of Bilge, Hamit Celebi, and 10 family members were among the dead, Anatolian said.
Local rivalry spilling into deadly feuds is not unheard of in southeast Turkey, although it is rare for the death toll to be so high. The scale of the latest attack would be of deep concern to the government, which is attempting to defuse tensions in the southeast born of separatist conflict.
The Turkish newspaper Hurriyet said on its website that the attack took place in mid-evening and that four unidentified gunmen had been involved in the attack and then escaped.
The last line and the bit about the sandstorm seem to imply otherwise, at least so far. The eight who have been arrested are probably witnesses and/or potential informants who they believe can identify the gunmen, rather than the gunmen themselves.
"Do I really look like a guy with a plan? Y'know what I am? I'm a dog chasing cars. I wouldn't know what to do with one if I caught it! Y'know, I just do things..." --The Joker
