Two people have been killed and over 100 have been injured in two blasts that rocked a rally organised by the largely Kurdish Peoples' Democratic Party's (HDP) in the southeastern Turkish province of Diyarbakır, according to turkey's culture minister.
Journalist Mat Nashed, a reporter for Middle East Eye at the scene, said that four people had been killed.
Initial reports suggest that two separate explosions occurred five minutes apart, shortly before party's leader Selahattin Demirtas was due to address the thousands of supporters who had gathered at the march ahead of the election slated for Friday 7 June.
So far there is confusion about what exactly caused the incident, with some suggesting that it could a faulty electricity distribution unit could have been responsible although Energy Minister Taner Yıldız ruled out this claims.
"There was an external intervention to the power distribution unit," he said. "Our inspection has clearly showed that the source of the explosion was not the power distribution unit. Its door was damaged with pressure coming from outside to inside and not vice versa.”
Following the blast, Demirtas urged his supporters to remain calm and not "respond to provocations" adding that the blast’s cause had not yet been firmly established.
"It is thought-provoking that this incident has taken place before the election," Demirtaş told Turkey's CNN Turk television from Diyarbakır. "Whatever the cause of the blast, I am calling on the people of Diyarbakır to keep calm."
Turkish Prime Minister Ahmet Davutoglu has vowed to apprehend those responsible.
"We will look into whether it is a power distribution unit explosion or an assasination [attempt], or any kind of provocation, and we will announce the result as soon as possible," he said.
"As we have caught the perpetrators of attacks against the HDP in the past, we will catch any perpetrators here.”
Steven Cook, a US specialist on Turkey from the Council on Foreign Relations, commented: "To state the obvious, someone is trying to provoke the Kurds into violence a few days before the elections".
After the incident some activists threw stones in anger at the police, with the security forces then using tear gas to keep control, AFP reported.
The rally was to have been one of the HDP's key campaign events, as Diyarbakir is the most significant city in the Kurdish-majority southeast that is the bedrock of its support.
The HDP has been targeted by several attacks ahead of Sunday's elections and clashes with Turkish nationalists at its rally in the eastern city of Erzurum on Thursday left dozens wounded.
According to the party, it has been violently targeted more than 70 times during the election campaign.
Earlier this week, unidentified gunmen opened fire on a HDP campaign bus in the Kurdish-majority eastern Bingol province, killing the driver.
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.
"If I were the president, I would not only work to ensure that the HDP has a seat in the parliament, but all other [non-represented] parties as well. It is important that all parts of the society have representatives [in the parliament]," Demirtas said after the blast.
"Otherwise, those who are left out - and we have been left out for years, and know the pain - would not feel like the parliament belongs to them. And when they feel that way, they start seeking other means, which would create tension in the society."
Demirtas said that the current election threshold was not just the HDP's problem, but "of about 25 parties which are not represented in the parliament".
"When the HDP surpasses the threshold, this will mean an increase in people's faith in democratic politics, and freedom of religion, and identity," he said, adding that the only reason they were in politics was to prevent violence from becoming those "other means".