The gunman said in Turkish “We die in Aleppo, you die here” during the shooting which left Ambassador Andrei Karlov dead.
The attacker himself was then fatally shot by cops after he had injured Ambassador Karlov and at least three others.
The Russian envoy was delivering a speech at an art gallery in the capital of Ankara when the gunman, reportedly an off-duty police officer, fired a shot into the air and then shot the ambassador in a suspected radical Islamic attack.
Russia’s state-runnews agency, RIA, reported Mr Karlov had died. The assassination and aftermath were captured on camera, showing the ambassador speaking at a podium before collapsing to the floor.
62-year-old Andrei Karlov, was taken to a nearby hospital following the shooting but was later pronounced dead, Russia’s Foreign Ministry said. The career diplomat, who was married with a son, started his diplomatic career in 1976 and served in diplomatic posts to Korea before being named ambassador to Turkey in 2013.
Karlov was several minutes into a speech at the embassy-sponsored exhibition in the capital when a man wearing a suit and tie shouted “Allahu akbar” and fired multiple shots, striking Karlov.
Photos showed the attacker, wearing a black suit, standing behind the ambassador, his hands clasped before pulling out a handgun in his right hand to shoot.
After shooting the ambassador, the gunman extended his right arm and pointed the gun, gestured with his left index finger pointed into the air.
Three others were reportedly wounded as the shooting continued and people fled for their lives. The gunman allegedly entered the gallery with police identification, and Mr Karlov reportedly did not have a security detail with him.
Mr Karlov was attending the opening of an exhibition at Ankara’s Centre for Contemporary Arts when the gun attack occurred.
The Kremlin said Russian President Vladimir Putin was holding an emergency meeting in the wake of the assassination.
Turkish Police officers secure the crime scene zone around the art gallery
Russia is Syria’s most powerful ally and has played a significant role in the Syrian government’s attempts to eradicate rebel groups across the country.
In recent weeks pro-government forces have made rapid advances on rebel-held territory in war-torn Aleppo, leaving many people dead or wounded.
After rebels were driven into an enclave in eastern Aleppo after heavy bombing a ceasefire was brokered by Russian and Turkish officials.
It included a plan to evacuate thousands of rebels and civilians, including women and children, from Aleppo to rebel-held territory in Idlib province in north-western Syria.
U.S. State Department issued a statement, condemning the attack. Spokesman John Kirby said: “We condemn this act of violence, whatever its source,” Kirby said. “Our thoughts and prayers are with him and his family.”