Turkish Prime Minister Binali Yildirim said Friday's bombing was carried out by the Kurdistan Workers Party (PKK) which has regularly targeted security forces since ending a truce in 2015.
The early morning attack on a police headquarters in the Kurdish-majority of Diyarbakir left 11 people dead, including two police, and over 100 wounded.
The state-run Anadolu news agency said the toll rose to 11 on Saturday after two more civilian victims succumbed to their wounds.
It left a swathe of devastation, blowing out the entire front of a nearby apartment block and leaving the surroundings covered in rubble.
Emergency workers on Saturday began to sift through the damage while residents arrived to pick up whatever belongings they could salvage, an AFP photographer said.
The pro-Kurdish People's Democratic Party (HDP) said six of its MPs, including its co-leaders, had narrowly escaped injury in the attack as they were being held in the police complex following their detention overnight.
The US-based SITE Intelligence Group cited an "insider source" for the IS-affiliated Amaq news agency as saying that "Fighters from the Islamic State detonated an explosives-laden vehicle parked in front of a Turkish police headquarters in Diyarbakir in southeastern Turkey."
If confirmed, the claim would be the first ever by IS for an attack in Turkey, although it has been blamed over the last year for a series of strikes against Kurdish activists, tourists and on Istanbul airport.
There has so far been no denial or claim of responsibility from the PKK.
IS call for attacks
In an audio message released earlier this week, reclusive IS leader Abu Bakr al-Baghdadi broke a nearly year-old silence to call for attacks against Turkey, as well as Saudi Arabia, and for his fighters to hold their ground in their stronghold of Mosul, Iraq.
Ankara has troops stationed at a base just outside Mosul and Turkish President Recep Tayyip Erdogan's escalating rhetoric has raised fears of an expanded Turkish military intervention in Iraq.
Yildirim said the PKK had again showed its "ugly face" with the attack.
The HDP meanwhile said its co-leaders Selahattin Demirtas and Figen Yuksekdag as well as four other MPs had been brought to the police complex overnight after their detention early Friday.
It said in a statement Demirtas had been taken to court just before the attack and Yuksekdag was in the complex when it happened.
Without directly saying its MPs were the target, it noted that the minibus packed with explosives had blown up early following an alert from a taxi driver.
"All the facts must be revealed about this attack which was planned to be even more devastating and did not reach its intended target," the HDP said.
The two co-leaders and 10 other HDP MPs have now been placed under arrest ahead of trial by the courts.
Demirtas and Yuksekdag have been transferred by air to prisons in the western regions of Edirne and Kocaeli respectively, well away from Diyarbakir.
