The UN Secretary-General Antonio Guterres condemned in the “strongest possible terms” Friday’s deadly terrorist attack at a concert hall outside Moscow.

Gunmen stormed the Crocus City Hall in Krasnogorsk, killing over 60 people and injuring another 145 others as a group of armed men, wearing combat fatigues, opened fire at location on Friday night, BBC and Reuters reported, citing Russia’s FSB Federal Security Service.

According to Russian news reports, the terrorists threw explosives, triggering a massive fire at the Hall, located on the western edge of Moscow. Videos on social media showed huge plumes of black smoke rising over the building, Reuters reported.

“The Secretary-General conveys his deep condolences to the bereaved families and the people and the Government of the Russian Federation,” said his Deputy Spokesperson Farhan Haq. “He wishes those injured a speedy recovery.”

The Security Council also condemned “the heinous and cowardly terrorist attack” in a press statement released on Friday evening.

“This reprehensible act of terrorism resulted in the grievous loss of dozens of lives,” Council members said, expressed their deepest sympathy and condolences to the families of the victims and to the Russian people.

The Council members reaffirmed that terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security and underlined the need to hold perpetrators, organizers, financiers and sponsors of these reprehensible acts of terrorism accountable and bring them to justice.

They urged all States, in accordance with their obligations under international law and relevant Security Council resolutions, to cooperate actively with the Russian Government as well as all other relevant authorities in this regard.