Gunmen opened fire on a music venue outside of Moscow, Russia today (March 22), killing at least 40 people and wounding more than 100, according to multiple reports. Crocus City Hall was attacked prior to the concert by four or five armed individuals dressed in camouflage, who shot openly at concert-goers and threw a “grenade or incendiary bomb” into the building. This started a fire and partially collapsed the roof, according to Russian state-owned news network RIA Novosti.

The band Picnic was set to perform before the attack occurred. According to BBC News, there was verified, close-up footage of “gunmen shooting indiscriminately.” Additionally, images show the complex on fire with black smoke billowing from the roof.

At least 100 people were evacuated from the concert hall by firefighters, and people inside the venue took video and posted it to social media. Videos verified by the BBC show concert-goers being evacuated, then gunshots ringing out and panic ensuing. People were shown hiding and huddled together inside the venue.

The BBC reports four armed individuals carried out the attack, while according to US News & World Report, there were at least five attackers. Russian media agencies reported at least two incendiary blasts at the venue, while others reported that the gunmen barricaded themselves inside. According to CNN, per the Main Directorate of the Ministry of Emergency Situations of the Russian Federation, firefighters and rescuers are still attempting to retrieve people from the roof.

All public events have been canceled in Moscow this coming weekend. Moscow Mayor Sergei Sobyanin addressed the public with a statement, saying, “Today a terrible tragedy occurred in the Crocus City center. My condolences to the loved ones of the victims. I gave orders to provide all necessary assistance to everyone who suffered during the incident.”