An unknown assailant has shot and killed the deputy mayor of Istanbul's Sisli district in the head, Turkish broadcaster NTV reported.
It was not immediately clear whether the incident was linked to Saturday's abortive military coup in which more than 200 people were killed.
NTV reported that the assailant had entered the office of deputy mayor Cemil Candas and then gun shots were heard.
Turkey's main opposition Republican People's Party (CHP) runs the prosperous Sisli district. Along with other opposition parties the CHP has condemned the attempted coup.
Earlier, MPs were reportedly told to evacuate the Turkish parliament building in Ankara over an unspecified security threat, according to an opposition politician, reports the Independent.
The Cumhurriyet newspaper quoted the Peoples' Democracy Party member Ziya Pir as saying: "We have been informed of an attack. The Meclis is being evacuated."
The development comes as the United States and European Union on Monday sternly warned Turkey to respect the rule of law after President Recep Tayyip Erdogan's government launched a massive crackdown following the failed coup.
Confusion over general's confession
Turkey's state-run news agency says that the former Air Force commander accused of being the coup ringleader has confessed to a role in the failed coup attempt.
Anadolu Agency quotes Gen. Akin Ozturk as telling prosecutors questioning him in Ankara that he "acted with the intention of carrying out a coup." Before his detention, Ozturk had denied in a statement that he was involved in the uprising, insisting that that he had worked to quash the coup.
But two private broadcasters said the general had denied playing a role.
NTV quoted him as saying: "I am not someone who has planned or directed the coup attempt... I don't know who did."
Recep Tayyip Erdogan calls for extradition
Turkish President Recep Tayyip Erdogan, speaking to CNN through his translator on Monday, said Turkey will submit a formal request within days for the extradition of Muslim cleric Fethullah Gulen from the United States. Erdogan blames Gulen for the failed coup attempt.
Wikileaks to release Turkey documents
Wikileaks says it is preparing to release more than 100,000 documents related to the Turkish government in the wake of a failed coup.
"Get ready for a fight as we release 100k+ docs n #Turkey's political power structure," the organisation posted on Twitter. Founded by Julian Assange in 2006, the Wikileaks whistleblowing group is best known for its release of classified US diplomatic cables in 2010 that embarrassed Washington and its allies and risked undermining US diplomacy.
NATO's chief has joined with others who are calling for Turkey's leadership to respect the rule of law in its reaction to the failed attempt at a military coup.
"I have spoken to President Recep Tayyip Erdogan in the aftermath of the attempted coup in Turkey," NATO Secretary-General Jens Stoltenberg said Monday in a statement. "I welcomed the strong support shown by the people and all political parties to democracy and to the democratically elected government. The Turkish people have shown great courage." As he did early on Saturday, Stoltenberg condemned the attempted coup in Turkey and reiterated his full support for Turkey's democratic institutions.
"Being part of a unique community of values, it is essential for Turkey, like all other allies, to ensure full respect for democracy and its institutions, the constitutional order, the rule of law and fundamental freedoms," the NATO chief said. He called Turkey a "valued NATO ally," and offered his condolences to the families of the innocent people who lost their lives in the takeover attempt.