Vehicles of Russian emergency services are parked near the burning Crocus City Hall concert venue, following a reported shooting incident, outside Moscow, Russia, March 22.

Maxim Shemetov/Reuters

At least 60 people have been killed and 145 others injured after several gunmen wearing camouflage burst into a concert venue on the outskirts of Moscow Friday. A fire broke out with flames visible from miles away. The whereabouts of the gunmen remain unknown.

The U.S. believes a group known as Islamic State Khorasan Province, or ISIS-K, is responsible, an administration official told NPR. The group, based in eastern Afghanistan, had claimed responsibility on its Telegram channel.

The U.S. warned Russia earlier this month that it had information about a planned terror attack in Moscow, potentially targeting concerts, said National Security Council spokeswoman Adrienne Watson in a statement.

Concertgoers had gathered at Moscow's Crocus City Hall venue to see the veteran Russian rock band Picnic when several armed gunmen in military fatigues entered.

Witness videos on social media show at least three attackers firing at bystanders as they attempted to hide. Other images show people lying on the ground in the main concert hall before a fire breaks out and spreads, trapping some inside. Several people were spotted on the venue's roof.

Moscow Mayor Sergey Sobyanin said "a huge tragedy has occurred" as the number of dead is expected to rise, and expressed his condolences.

Russian Rosguardia (National Guard) servicemen secure an area near the Crocus City Hall on the western edge of Moscow, Russia, Friday, March 22, 2024. Several gunmen have burst into a big concert hall in Moscow and fired automatic weapons at the crowd, injuring an unspecified number of people.

Vitaly Smolnikov/AP

Some Russian officials are suggesting there must be some Ukrainian role, a claim the Ukrainians deny. Mykhailo Podolyak, an advisor to Ukrainian President Volodymyr Zelenskyy tweeted "Ukraine certainly had nothing to do with the shooting in the Crocus City Hall. It makes no sense whatsoever."

The White House issued a statement calling the attack "terrible" and saying there was "no indication at this time" of a Ukrainian role in the attack.

National Security Council spokesman John Kirby said the images of the shooting were "horrible and hard to watch." The U.S. embassy in Moscow has warned U.S. citizens to avoid the area.

A medic stands near ambulances parked outside the burning building of the Crocus City Hall on the western edge of Moscow, Russia, Friday, March 22, 2024. Several gunmen have burst into a big concert hall in Moscow and fired automatic weapons at the crowd

Vitaly Smolnikov/AP

Moscow was the scene of a hostage crisis at the Dubrovka theater in 2002, in which Chechen gunmen demanding the withdrawal of Russian troops from Chechnya took some 800 theatergoers hostage. A raid by Russian security forces to end the crisis killed or caused the deaths of 172 people.

Russian Foreign Ministry spokesperson Maria Zakharova called on the international community to condemn the incident, calling it "a monstrous crime."

This is a breaking news story and will be updated.