A prominent pro-Kurdish lawyer was shot dead on Saturday in Turkey's predominantly Kurdish southeastern city of Diyarbakir.
Tahir Elci, the chairman of the Diyarbakir Bar Association, was caught in the crossfire between Kurdish rebels and security forces while making a press statement in Diyarbakir, Turkish media reported.
Elci, a highly influential figure with Kurds in Turkey, died after he was hospitalised, state broadcaster TRT said.
In an address in the western city of Balikesir, Turkish President Recep Tayyip Erdogan confirmed the death of Elci. "This incident shows how Turkey is right in its determination in the fight against terrorism," Erdogan said.
Two other policemen died in the firefight and a number of journalists were wounded, witnesses said.
Prime Minister Ahmet Davutoglu said there were two possibilities regarding the death of Elci. It may have been an assassination, or he may have been caught in an exchange of fire during clashes between the police and the outlawed Kurdistan Workers' Party (PKK), Davutoglu said.
Speaking to Al Jazeera, a senior government official said: "We are determined to shed light on today's fatal incident in Diyarbak?r. An official investigation has been launched and we have assigned four inspectors to this case."
"At this time, we believe that Mr. Elci may have been caught in the crossfire but we aren't ruling out the possibility that a third party directly targeted him," he added.
The official spoke on condition of anonymity, as he was not authorised to discuss the case with the media.
The Diyarbakir governor's office declared a curfew in the area after the incident.
Protests later broke out in Diyarbakir and elsewhere denouncing the killing.
In Diyarbakir, police used pressurised water against a group of protesters who hurled rocks and fire crackers.
Police also dispersed hundreds of people who gathered in central Istanbul chanting: "We are all Tahir, we are all Elci."
Hundreds of supporters of Elci, who were trying to get to Diyarbakir for the lawyer's funeral on Sunday morning, were being blocked by police in several parts of the country, sources told Al Jazeera.
Turkish authorities arrested Elci in October for saying the PKK was not a terrorist organisation. However, he was released pending trial shortly thereafter.
However, he has also been critical of the PKK, demanding that certain elements of the group should leave Diyarbakir.