ISTANBUL — Russia’s ambassador to Turkey was assassinated at an Ankara art exhibit on Monday evening by a lone Turkish gunman shouting “God is great!” and “don’t forget Aleppo, don’t forget Syria!” in what the leaders of Turkey and Russia called a provocative terrorist attack.
The gunman, described by Turkish officials as a 22-year-old off-duty police officer, also wounded at least three others in the assault on the envoy, Andrey G. Karlov, which was captured on video. Turkish officials said the assailant was killed by other officers in a shootout.
The assassination, an embarrassing security failure in the Turkish capital, forced Turkey and Russia to confront a new crisis tied directly to the Syrian conflict, now in its sixth year.
The longer-term implications for the Russia-Turkey relationship, which had been warming recently after plunging a year ago, were not immediately clear. But some analysts played down the notion that the assassination would lead to a new rupture, saying it could conversely bring the countries closer together in a shared fight against terrorism.
In an emergency meeting with Foreign Minister Sergey V. Lavrov and other top officials, Mr. Putin said, “There can be only one answer to this — stepping up the fight against terrorism, and the bandits will feel this.”
Mr. Erdogan, in a speech late Monday night, said the assassination was a provocation meant to derail efforts by Turkey and Russia to collaborate more closely on regional issues and economic ties.
“We know that this is a provocation aiming to destroy the normalization process of Turkey-Russia relations,” Mr. Erdogan said. “But the Russian government and the Turkish republic have the will to not fall into that provocation.”
The assassination came after days of protests by Turks angry over Russia’s support for the Syrian government in the conflict and the Russian role in the killings and destruction in Aleppo, the northern Syrian city.
The Russian envoy was shot from behind and immediately fell to the floor while speaking at an exhibition of photographs, according to multiple accounts from the scene, the Contemporary Arts Center in the Cankaya area of Ankara.
The gunman, wearing a dark suit and tie, was seen in video footage of the assault waving a pistol and shouting in Arabic: “God is great! Those who pledged allegiance to Muhammad for jihad. God is great!”