The Russian ambassador to Ankara, Andrei Karlov, has been killed in a gun attack in Turkey.
The Russian Foreign Ministry said the ambassador had been taken to hospital and had died of his wounds.
"We regard this as a terrorist act," said ministry spokeswoman Maria Zakharova.
Reports say the gunman was a 22-year-old police officer who worked in Ankara.
Several other people were reportedly injured in the attack, a day after protests in Turkey over Russia's military intervention in Syria.
According to Russian TV, the ambassador had been attending an exhibition at a photo gallery called "Russia as seen by Turks". Reports suggest the gunman was later killed by police.
Video of the event shows Mr Karlov making a speech when gunshots ring out.
The camera pulls back to show a smartly dressed gunman, wearing a suit and tie, waving a pistol and shouting.
He can be heard yelling "Don't forget about Aleppo, dont forget about Syria" and uses the Islamic phrase "Allahu Akbar" (God is great).
While there were protests in recent days, on a political level the Turkish and Russian governments have been co-operating in the Aleppo ceasefire operation, the BBC reports.
It is too early to know the motives of the attacker, who has not yet been named. Some reports say he entered the art gallery using a police ID card, the BBC says.
Foreign and defence ministers of Russia, Iran and Turkey are due to discuss the future of Syria in Moscow on Tuesday. Leonid Slutsky, chairman of the State Duma, said the talks would go ahead despite the killing of the ambassador.
- Reuters / BBC