Three helicopters were dispatched to the scene, the agency reported. An explosion was reported at 9:32 p.m. local time, and RIA Novosti reported that the fire had intensified. The roof near the stage was collapsing at around 10 p.m. local time, RIA Novosti reported.

There was no report of who might be responsible for the attack, but state media agencies reported that there were up to five perpetrators. Russia’s Investigative Committee, the country’s equivalent to the F.B.I., said it had opened a criminal case into a terrorist act and dispatched its investigators to the scene.

Emergency services said more than 100 people had already been evacuated from the building.

Videos verified by The New York Times show multiple people holding guns entering Crocus City Hall, a shopping mall and concert venue in Krasnogorsk, a suburb on the northwestern outskirts of Moscow. The videos show people wounded on the ground.

In videos filmed inside the concert hall, audience members awaiting a performance by the veteran rock band Piknik are heard screaming, and there are repeated gunshots from outside of the hall. Other videos filmed from a highway outside of the building show parts of it on fire producing heavy smoke.

Video

“At least three people in camouflage burst into the ground floor of Crocus City Hall and opened fire with automatic weapons,” a correspondent for another state news agency, RIA Novosti, reported from the scene. “There are definitely wounded.”

RIA Novosti said that a special police unit was working inside the building alongside firefighters. Images posted to social media from the scene showed bodies laid on the ground outside the venue.

Moscow’s mayor, Sergei S. Sobyanin, said that multiple people had been killed and called it a “terrible tragedy.” He said all large events planned for the weekend would be canceled. In St. Petersburg, more than 400 miles from Moscow, shopping centers were also being evacuated, according to the independent outlet Bumaga.

Shootings are rare in Russia, a country where the state tightly regulates the possession of firearms. One of the deadliest ones occurred in 2022, when a gunman killed 18 people and wounded 23 others in a school in the town of Izhevsk.

On March 7, the U.S. Embassy in Moscow issued a security alert warning that its personnel were “monitoring reports that extremists have imminent plans to target large gatherings in Moscow, to include concerts.” The statement warned U.S. citizens that an attack could take place in the next 48 hours.

Pro-Kremlin voices seized on the U.S. Embassy’s warning to paint America as trying to scare Russians. On March 19, President Vladimir V. Putin called the statement “obvious blackmail” made with “the intention to intimidate and destabilize our society.”

The attack came the same day as 165 missiles and drones attacked Ukraine, constituting what the U.S. ambassador to Ukraine, Bridget Brink, said was “the largest attack against Ukraine’s energy grid since the start of Russia’s war.”

But there was no immediate indication of any Ukrainian involvement in the Moscow attack, or of the identity of the assailants.

John Kirby, the White House’s national security communications adviser, said that there was “no indication at this time that Ukraine, or Ukrainians, were involved in the shooting.” In comments to reporters, he said, “I would disabuse you at this early hour of any connection to Ukraine.”