UPDATE (12:42 p.m.): The assassin has been identified as an Ankara police officer.
BREAKING: The assailant is identified as Mevlüt Mert Altintas who is a police officer from Ankara. pic.twitter.com/UeIrgCMs57— Turkey Untold (@TurkeyUntold) December 19, 2016
UPDATE (12:34 p.m. ET): CNN has obtained photos and videos from the assassination. Warning: The footage is very disturbing.
UPDATE (12:30 p.m. ET): The assassin shouted, "don't forget about Aleppo, don't forget about Syria" during the attack, according to the BBC.
UPDATE (12:18 p.m. ET): The ambassador has died.
BREAKING: Russian Ambassador Andrey Karlov dies after being shot in Ankara - RIA https://t.co/dIQxJOd7iP— BNO News (@BNONews) December 19, 2016
UPDATE (12:14 p.m. ET): The U.S. State Department has condemned the attack.
"We condemn this act of violence, whatever its source," said State Department spokesman John Kirby in a statement. "Our thoughts and prayers are with him and his family."
UPDATE: The assassin is dead.
BREAKING: Private NTV news channel reports Turkish police have fatally shot gunman who attacked Russian ambassador.— The Associated Press (@AP) December 19, 2016
UPDATE: More details are surfacing from the attack.
Russian Ambassador Andrey Karlov has been shot at an event in Ankara, Turkey, according to reports from Turkish media. He has been taken to the hospital and is reportedly in critical condition.
Karlov has been an ambassador to Russia since July 2013. He was visiting a photography exhibition at Ankara's Contemporary Arts Center when the gunman approached.
The gunman has been "neutralized," according to Reuters.
This post has been updated.