Russian ambassador to Turkey, Andrey Karlov, was on Monday killed during an art exhibition in Ankara, capital of Turkey.
The gunman who claimed to be a Turkish policeman cried “Aleppo” and “revenge” before shooting Karlov from behind.
The attacker shouted “Allahu Akbar” and fired at least eight shots, according to an AP photographer who was present.
Karlov reportedly died at the scene.
Turkish officials said the assassin entered the building claiming he was a police officer.
The attacker was said to have first shot Karlov in the back, before ordering people to leave the room. He then reportedly shot a second time as he lay on the floor. Turkish special forces have surrounded the gallery, believing the attacker to still be inside.
Meanwhile, Russia has described that attack as an act of terror.
The Russian foreign ministry said it was in contact with Ankara over the events, RIA Novosti reported.
President Vladimir Putin called an urgent meeting with foreign minister Sergei Lavrov and the heads of the security services.