Russian President Vladimir Putin vowed revenge on Monday for the assassination of Russia's ambassador to Turkey, who was shot in the back by a renegade Turkish special forces police officer during an apparent Islamic terror attack.

Putin spoke with other members of his cabinet in a brief meeting that was broadcast and translated on RT and came mere hours after Ambassador Andrei Karlov was brazenly gunned down.

“We have to know who organized the killing, who gave orders to the assassin," said Putin, who also pledged to punish those responsible.

"The fight against terrorism will only be stepped up," he said.

Putin called Karlov an "outstanding diplomat" and said he knew him personally. He called for a memorial to be erected in his honor.

Putin said an investigation into the incident was ongoing.

Photographers captured the chilling moment 22-year-old Mevlut Mert Altintas opened fire inside an Ankara art exhibit Monday, killing Karlov and wounding at least three others as Altintas shouted jihadi propaganda before being killed.

Still and video cameras were trained on Karlov, who was giving a speech at the Ankara Center for Contemporary Art when a man wearing a dark suit suddenly shot Karlov in the back. Video captured the incident and shows Karlov grimacing and falling to the ground as the gunman, later identified as Altintas, moves toward his body.



Click to see pictures of the attack taken from inside the hall

Turkish Interior Minister Suleyman Soylu said Altintas had been working for the riot police squad in Ankara for the past 2 1/2 years. Witnesses said he entered the building with a police ID.

Ankara Mayor Melih Gokcek told AFP the attack was aimed at ruining relations between Turkey and Russia. The two countries had begun normalizing ties in June 2016. That followed a strained period caused when a Turkish combat aircraft shot down a Russian military jet in November 2015.

Click here to see graphic video of the attack in Ankara

Altintas could be heard yelling "Allahu akbar" and shouting Arabic verses popular with Jihadis, according to a FoxNews.com translation of video of the attack.

"Do not forget Aleppo, do not forget Syria...we die there every day...We are not safe here in the streets when they are dying over there," he said.

"You’ll never be safe as long as other mothers are unsafe...Keep filming me, only my dead corpse will leave this building."

Altintas then turned back to the Syria conflict: "Whoever is responsible for this [tyranny] is going to pay."

Shortly after the attack ended, the U.S. State Department tweeted about a reported shooting in the area of the U.S. Embassy in Ankara and warned U.S. citizens to stay away. The State Department later clarified that it was referring to Karlov's shooting and not a new incident.

U.S. Secretary of State John Kerry called the assassination a "despicable attack." Kerry said the killing was "an assault on the right of all diplomats to safely and securely advance and represent their nations around the world."

Kerry said the U.S. was ready to offer help to Russia and Turkey in the investigation of the attack.

Karlov, 62, had been Russia's ambassador to Turkey since July 2013. He was Russia's ambassador to North Korea from 2001-2006.

Karlov is survived by a wife and a son.

The Associated Press contributed to this report.