The Russian ambassador to Turkey, Andrei Karlov, has been shot while speaking at an art exhibit in the Turkish capital of Ankara.

Hurriyet Daily News reports three other people were injured in the attack, the shooter may still be in the building at the time of this report, and Karlov has not yet been taken to the hospital for treatment.

Hurriyet quotes the Russian embassy saying it believes “radical Islamists” were behind the attack, and notes that Turkish Foreign Minister Mevlut Cavusoglu is due in Moscow tomorrow for talks on the Syrian crisis with Russia and Iran.

CNN Turk is running a photo that appears to show the gunman:

Screen grab via @CNNTurk, photograph seems to show gunman on the right pic.twitter.com/ykWyAOvLqR — Piotr Zalewski (@p_zalewski) December 19, 2016

Update, 11:40 EST: Russia’s TASS news agency reports the exhibit Karlov was speaking at was a photo exhibit called “Russia in the Eyes of Turks.” The perpetrator is said to have fired shots in the air and shouted “Get out!” at the crowd.

Hurriyet Daily News had a reporter on the scene who confirmed the crowd ran after the gunman fired in the air, then Karlov was shot.

Update, 11:45 EST: According to Ragip Soylu, a reporter for the generally pro-Erdogan Daily Sabah, the attacker bypassed security by showing a police ID badge, and shouted something about Aleppo and Syria before he opened fire. More specifically, he is said to have shouted, “We die in Aleppo, you die here.”

Soylu also reports Karlov was shot “four or five times.” He has posted a photo that may be of the attacker, although noting this has not been confirmed by the authorities as yet:

The unconfirmed picture of the gunman in Ankara attack who targeted the Russian Ambassador pic.twitter.com/LEkcZdws2c — Ragıp Soylu (@ragipsoylu) December 19, 2016

Update, 11:55 EST: An Associated Press photographer who was in the auidence reports the gunman shouted “Allahu akbar!” before opening fire, as well as saying something in Russian, and fired at least eight shots. Karlow was several minutes into his prepared remarks before the attack began.

Turkish media is reporting that the gunman has been neutralized. CNN Turk is reporting that special forces entered the building and ended a “brief hostage situation.”

Another photo of the gunman in action:

PICTURE The gunman gestures near to Andrei Karlov on ground, the Russian Ambassador to Ankara, (AP Photo/Burhan Ozbilici) pic.twitter.com/D0iYqsmNld — Ragıp Soylu (@ragipsoylu) December 19, 2016

Update, 12:00 EST: The gunman has reportedly been killed by Turkish security forces:

UPDATE: The gunman shouted “we die in Aleppo, you die here” as he shot the Russian ambassador 5 times, he was then killed by security forces pic.twitter.com/rEBl3GCxdy — News_Executive (@News_Executive) December 19, 2016

Update, 12:05 EST: Turkish media are reporting that Ambassador Karlov has died of his wounds.

Update, 12:15 EST: Daily Sabah’s Ragip Soylu has posted video of the gunman during the attack:

#BREAKING The video shows the attack scene moments after Russian Ambassador shot to death. He shouts “don’t forget Aleppo, Syria” pic.twitter.com/xtX974W39t — Ragıp Soylu (@ragipsoylu) December 19, 2016

Although the identity of the shooter has not been confirmed at the time of this writing, there have been claims he really was a plainclothes policeman, and possibly even a member of the Ambassador’s security detail.

Update, 12:20 EST: Russian President Vladimir Putin is meeting with his Foreign Minister and the heads of Russian security services about the attack. A Foreign Ministry spokesman said the Russians were in contact with Turkish authorities.

Hurriyet Daily News has updated its report to quote the attacker shouting to the crowd, “I will not leave here alive, do not approach me.”

Update, 12:25 EST: Chilling video of the attack as it happened:

Terrifying video of a gunman shooting the Russian ambassador to Turkey as he shouts “Allahu Akbar” https://t.co/O4KAychWh8 — Alec Luhn (@ASLuhn) December 19, 2016

Update, 12:45 EST: Turkish media are reporting that the gunman has been identified as 22-year-old Mevlut Mert Altintas, a serving police officer in the Ankara special operations unit.

The attacker is 22 years-old Turkish police M.M.A from Ankara police special force department.. pic.twitter.com/7Ckf67ZlG9 — METIN GURCAN (@Metin4020) December 19, 2016

His cries during the assassination have been translated, according to a report at Business Insider. At first, he shouted in Arabic: “We’ve made an oath to Mohammed to die in martyrdom, [it is] revenge for Syria and Aleppo.”

Altintas then switched to Turkish and shouted, “Don’t forget Aleppo. Don’t forget Syria… You won’t be safe. Only my dead body will leave here.”

He was described as speaking Turkish with an “educated, Istanbul accent” with “no trace of foreign accent, Arab or otherwise.”

Update, 12:55 EST: Below is a better-quality video of the assassin’s rant after shooting the ambassador. More explicit videos capturing the moment of the shooting have also been posted; one such video can be found here. (WARNING: graphic content.)

https://www.youtube.com/watch?v=rjCS0i2uHU8

Update, 13:15 EST: The BBC quotes Turkish security sources who confirmed the assassin was a police officer, but they claimed he was off-duty when he attacked.

“We condemn this act of violence, whatever its source. Our thoughts and prayers are with him and his family,” said U.S. State Department spokesman John Kirby, while U.N. Ambassador Samantha Power took to Twitter to “strongly condemn the savage attack.”

“I condemn in the strongest terms the heinous attack on Ambassador Karlov tonight,” said the U.S. Ambassador to Turkey, John Bass.

“Shocked to hear of despicable murder of Russia’s Ambassador to Turkey. My thoughts are with his family. I condemn this cowardly attack,” said British Foreign Secretary Boris Johnson.

Update, 13:20 EST: According to a report from Turkey’s Andalou Agency, Andrey Gennadyevich Karlov was born in Moscow in 1954. He graduated from Moscow State Institute of International Relations in 1976, and then from the Diplomatic Academy in 1992. He has been Russia’s ambassador to Turkey since July 2013. He was married, and has a son.

Update, 13:30 EST: A reporter for Russia Today offers a different account of the jihadi’s status with the Turkish police than what we’ve been hearing until now:

Russian ambassador to #Turkey was killed by EX policeman, Turkish Haberturk reports. He was let go following anti-#Erdogan coup in July. — Maria Finoshina (@MFinoshina_RT) December 19, 2016

RT.com also reports that Turkish President Recep Tayyip Erdogan has spoken with Russian President Vladimir Putin by telephone after the assassination.

Another remarkable, chilling image from Ankara: Ambassador Karlov looking at a painting in the art gallery, while his killer looms out-of-focus in the background behind him.

The moment before: The Russian Ambassador to Turkey looks at a painting at a gallery in Ankara earlier today. Behind him, his assassin… pic.twitter.com/sZyJsTnAYo — Tunku Varadarajan (@tunkuv) December 19, 2016

Update, 13:45 EST: Statement from the Turkish embassy in Russia, as related by Russia’s TASS news agency: “An inhumane tragedy occurred today with our distinguished colleague Andrey Karlov. There is no person in their right mind who would not condemn this evil act. We grieve with all our hearts. We bring our deepest condolences to the people of Russia. This is our shared pain and loss.”

Some unredacted photos of the dead gunman have emerged. (WARNING: very graphic image of bloodshed at the link.)

Update, 13:50 EST: According to Middle East Monitor, Ambassador Karlov “had been part of discussions between Turkey that led to an evacuation of east Aleppo getting underway late last week.”

Social media accounts linked to ISIS and al-Qaeda are reportedly celebrating the assassination, even though neither organization has formally claimed Altintas as a member.

Update, 14:05 EST: Statement from National Security Council spokesman Ned Price at the White House on the assassination in Ankara:

“The United States condemns in the strongest terms the terrorist attack this morning in Kayseri, Turkey, which killed more than a dozen people and wounded many more. This cowardly attack appears to have targeted off-duty Turkish soldiers who were traveling on a public transit bus that was also transporting civilians. Our thoughts and prayers go out to the victims, their families and loved ones, and to all the people of Turkey. As President Obama told President Erdogan in their phone call on December 15, we stand united with Turkey, our NATO Ally, in our determination to confront and defeat all forms of terrorism.”

Update, 14:30 EST: There have been some accusations in Turkey that Altintas carried out his attack at the behest of Fethullah Gulen, the exiled cleric currently living in Pennsylvania who has been accused of masterminding the July coup attempt against President Erdogan. Turkey has been pressing the United States to extradite Gulen.

Perhaps the most prominent voice to openly accuse Gulen of involvement in the Karlov assassination thus far is Melih Gokcek, the mayor of Ankara.

“Russian Ambassador to Turkey got attacked basely. The only goal of this assassination is to ruin the relationship between Russia and Turkey,” Gokcek said on Twitter, as related by the UK Express. “Turkish and Russian officials will definitely find whoever responsible from this attack. But it is for sure, the ones who were responsible for downing of Russian Jet in the past, are responsible for this attack as well.”

This was a reference to the downing of a Russian warplane along Turkey’s border with Syria last November. Erdogan has accused the Turkish pilots who shot down the Russian plane of being linked to Gulen’s organization.

“Assailant is a policeman. According to what I have heard, he is a FETO member. The slogans of the assailant are just perception management,” Gokcek added. FETO stands for “Fethullah Terrorist Organization,” the Turkish government’s name for Fethullah Gulen’s followers.

The Express notes that Gokcek has a history of floating conspiracy theories, including an accusation that the British BBC news service was complicit in the terrorist bombing of Istanbul earlier this month. However, he’s not the only source for the theory that Altintas was a Gulenist.

Update, 14:45 EST: The mother and sister of gunman Mevlut Mert Altintas have reportedly been detained in the southwestern province of Aydin. Another report from Turkey says Altintas’ home has been searched, and his roommate has also been detained, as well as his father.

Update, 16:15 EST: Reuters quotes a senior security official in Turkey who said there are “very strong signs” the gunman belonged to Gulen’s organization.