More than 60 people have been confirmed dead, with another 140 others injured in a terror attack that the U.S. intelligence agencies previously raised the alarm about.

Moscow, the capital city of Russia, was hit with a great tragedy on Friday when Islamic terrorists opened fire in a packed mall, killing several people and leaving many others injured. The terror incident occurred at a sold-out concert at Crocus City Hall while the rock band Piknik was getting ready to perform on Friday night.

Footage of the incident went viral on social media and showed four men in military gear carrying automatic weapons and randomly shooting people inside the mall.

According to The Daily Wire, the terror attack came just two weeks after the U.S. government warned Americans in Moscow to avoid large public gatherings such as concerts as terrorists were planning a large-scale attack.

The security alert, which came out on March 7 from the U.S. Embassy in Moscow, warned that its personnel were “monitoring reports that terrorists were planning to attack large gatherings in Moscow. The embassy warned that the attack could take place within the next 48 hours.

“The Embassy is monitoring reports that extremists have imminent plans to target large gatherings in Moscow, to include concerts, and US citizens should be advised to avoid large gatherings over the next 48 hours,” the embassy said at the time.

According to The New York Times, the Islamic State —through an affiliated news agency— has claimed responsibility for the attack. U.S. security officials —including a senior counterterrorism official— who spoke to The Times, said they believe the attack was carried out by the Islamic State in Khorasan, a branch of the terrorist group that is active in Pakistan, Afghanistan and Iran.

Colin P. Clarke, a counterterrorism analyst at the Soufan Group, told The Times that ISIS-K has had its eyes on Russia. Clark noted that the terrorist group has focused many of its attacks on Russian President Vladimir Putin in propaganda videos.

“ISIS-K has been fixated on Russia for the past two years,” Clarke told the outlet. “ISIS-K accuses the Kremlin of having Muslim blood in its hands, referencing Moscow’s interventions in Afghanistan, Chechnya and Syria.”