Two explosions went off Friday at rally by the pro-Kurdish People's Democratic Party (HDP) in southeast Turkey, wounding dozens and adding to tensions two days ahead of tight legislative polls.
The two successive blasts rocked the rally in the southeastern city of Diyarbakir, said an AFP correspondent, who saw at least a dozen people injured, some with bleeding legs.
The HDP, which is campaigning hard in Turkey's most closely-fought election in over a decade, has been the target of repeated attacks ahead of the polls.
Ambulances arrived at the scene to take the injured away, with chaos on the square where the rally was due to be held, the correspondent said.
Reports said that the explosions were blamed on an electrical transformer at the rally, but it was not clear what caused it to fail.
Health Minister Mehmet Muezzinoglu said that around 50 people had been wounded, around half of whom had been hospitalised, the Anatolia news agency reported.
Some activists threw stones in anger at the police, and security forces then used tear gas and water cannon to and clear the area.
HDP officials also told supporters through loudspeakers to leave the scene as the rally had been cancelled.
The HDP's leader Selahattin Demirtas had been due to address the rally, which had mustered tens of thousands of supporters before the explosion.
The rally was to have been one of the HDP's key campaign events -- Diyarbakir is the most significant city in the Kurdish-majority southeast that is the bedrock of its support.
Speaking at a rally in the southern city of Gaziantep close to the Syrian border, Prime Minister Ahmet Davutoglu expressed his condolences to the injured and vowed a swift investigation.
"We will achieve results in the swiftest possible time over whether this is an attack or some kind of provocation," he said.
He appealed on citizens of Diyarbakir, one of Turkey's most volatile cities, to stay calm and beware of provocations.
"This issue should not provoke anyone," he said.
Dozens of people had been killed in the southeast and across Turkey in October 2014 in pro-Kurdish protests over the government's policy in Syria.
In a tweet, Demirtas also sought to calm tensions. "Peace will win, be sure of this and keep common sense," he said.
Clashes at the HDP's rally in the eastern city of Erzurum on Thursday left dozens wounded and a driver with severe burns after his vehicle was set alight.
Earlier this week, unidentified gunmen opened fire on a HDP campaign bus in the Kurdish-majority eastern Bingol province, killing the driver.
In May, two blasts targeting HDP's headquarters in the southern cities of Adana and Mersin injured several people.
In a tight campaign, the HDP is battling to exceed the tough 10 percent threshold required in Turkey to send MPs to parliament.
Should it succeed, the presence of HDP MPs could stymie plans by the ruling party to agree a new constitution to hand more power to President Recep Tayyip Erdogan.
In this election, the HDP has tried to broaden its appeal beyond its natural Kurdish base in the southeast to secular Turks, women and gays.
Meanwhile, the AKP has sought to blacken the party's name by claiming it is a front for the Kurdistan Workers Party (PKK) which has led a bloody separatist insurgency in the region for the past decades.