UN Secretary-General Ban Ki-moon has condemned the assassination of Russian Ambassador to Turkey Andrey Karlov in Turkish capital of Ankara, calling it as a “senseless” act of terror.

Earlier on Monday, Karlov, who served as Russian ambassador to Turkey since 2013, was shot dead by a gunman when he spoke at the opening of an art exhibition in Ankara.

“The Secretary-General is appalled by this senseless act of terror and emphasizes that there can be no justification for the targeting of diplomatic personnel and civilians,” said a statement released by Ban’s spokesperson, Xinhua news agency reported.

“The Secretary-General is following the unfolding situation closely and wishes the other people who were reportedly injured in the attack a speedy and full recovery,” it added.

The assassination came one day before Turkish Foreign Minister Mevlut Cavusoglu heads to Moscow for talks on Syrian with his Russian and Iranian counterparts.

According to Kremlin spokesman Dmitry Peskov, Russian President Vladimir Putin has been informed of the attack, and is planning a consultation with the foreign ministry and the country’s security services.