Turkish President Recep Tayyip Erdogan has strongly condemned the assassination of Russian ambassador to Ankara, describing it as a “provocation” aimed at ruining Turkey-Russia ties.

“Turkey-Russia relations were vital for the region and those who aim to harm ties are not going to achieve their goals,” Erdogan said in a televised message on Monday, Xinhua news agency reported.

The Turkish President said he had a phone conversation with his Russian counterpart Vladimir Putin, who offered to send security officers to Turkey for the investigation.

The Turkish Foreign Minister Mevlut Cavusoglu is expected in Moscow on Tuesday for talks on Syria with his Russian and Iranian counterparts.

Earlier on Monday, a gunman in a black suit and tie shot dead the Russian Ambassador to Turkey Andrey Karlov as he was speaking at the opening of a photographic art exhibition in the capital city of Ankara, titled “Russia through Turks’ eyes.”

The gunman shouted “Don’t forget Aleppo. Don’t forget Syria. As long as our brothers are not safe, you will not enjoy safety. Whoever has a share in this oppression will pay for it one-by-one. Only death will take me away from here,” according to Turkish security sources.

The gunman was shot dead at the scene and identified as 22-year-old Turkish police officer Mevlut Mert Altintas, according to Turkish Interior Minister Suleyman Soylu.

He had been on duty for two and a half years at the riot police unit in Ankara.

Three other wounded people were taken to Guven Hospital in central Ankara for treatment.

Turkish Foreign Ministry also strongly condemned the attack.

“It’s been learned with great sorrow that Andrey Karlov, the Russian ambassador, lost his life as a result of an armed attack during the opening of a photo exhibition,” the Turkish Foreign Ministry said in a written statement on its website.

It said “all the connections of this incident will be brought to light and those responsible will be brought before the court.”

“We will not allow this attack to overshadow Turkish-Russian friendship,” it added.

Moscow and Ankara were in the process of normalising ties after the latter shot down a Russian warplane on November 24, 2015 claiming airspace violation.