Warning: This story contains images and video that may disturb some viewers.
Turkish police have detained the sister and mother of the gunman who shot dead the Russian ambassador at an art gallery in the Turkish capital, broadcaster CNN Turk reports.
Turkey's interior minister has identified the gunman as 22-year-old Mevlüt Mert Altıntas, from the Ankara police department's riot unit.
A video showed Altintas shouting: "Don't forget Aleppo, don't forget Syria!" and "Allahu Akbar (God is Greatest) as screams rang out. He paced about and shouted as he held the gun in one hand and waved the other in the air.
Russia's foreign ministry earlier confirmed that the ambassador, Andrey Karlov, had died in the attack on Monday.
Turkish state media earlier reported that Altintas had been "neutralised" following the attack.
Two security sources told Reuters he was not on duty at the time.
Altintas was smartly dressed in black suit and tie and stood, alone, behind the ambassador as he made a speech at the art exhibition, a person at the scene told Reuters.
Waving the gun at visitors he shouted: "Only death will remove me from here. Everyone who has taken part in this oppression will one by one pay for it."
Local media reported he fired eight shots - some after the Ambassador was already on the ground.
Photographers at the scene captured shots of Altintas dressed in a suit, brandishing a pistol.
"We consider this to have been a terrorist attack," said Russia Foreign Ministry spokeswoman Maria Zakharova.
"Terrorism will not pass. We will fight it decisively."
New Zealand's Ambassador to Turkey called Mr Karlov's death a "tragic assassination".
"Condolences to his family, colleagues, loved ones, country. RIP Amb Karlov," Jonathan Curr wrote on Twitter.
Mr Karlov was reportedly involved in discussions around the evacuation of Aleppo, which was underway Tuesday morning (NZ time).
Russian President Vladimir Putin has called an urgent meeting with high-ranking officials and has been in touch with Turkish officials in Ankara. The two countries haven't seen eye-to-eye in recent years, with disagreements over the situation in Syria and the downing of a Russian jet by Turkish forces in 2015.
Mr Karlov started his diplomatic career in the mid-1970s, and spent much of the USSR's latter years posted to North Korea. In the 1990s he helmed the embassy in South Korea, before moving back to the North in 2001.
He became Russian Ambassador to Turkey in 2013.
The US State Department also condemned the attack.
Reuters / Newshub.