This video says about itself:
19 December 2016
A news photographer captured the moment a well-dressed attacker opened fire inside an Ankara art exhibit Monday, shooting and killing Russia’s ambassador to Turkey and wounding at least three other people in an apparent … terror attack.
Still and video cameras were trained on Russian ambassador Andrey Karlov, who was giving a speech when a man in short hair and a dark suit suddenly shot Karlov in the back. Video captured of the incident shows Karlov grimacing and falling to the ground as the gunman moving toward his body. An Associated Press photographer on the scene took several images of the gunman and Karlov lying on the ground.
From Reuters news agency:
Russian Ambassador Shot And Killed In Turkish Capital Of Ankara
The ambassador was giving a speech at a photo exhibit when he was gunned down.
12/19/2016 11:33 am ET | Updated 38 minutes ago
See also here.
The murderer, an off duty Turkish policeman, used the war in Syria, in which the Turkish and Russian governments support opposing sides, as pretext for this crime.
One should hope this will not increase the danger of war between Russia and Turkey; as it increased when the Turkish air force shot down a Russian aircraft and a Turkish neonazi in Syria murdered the Russian pilot.