Here’s the latest on the attack in Russia.

Several gunmen opened fire at a popular concert venue on the outskirts of Moscow on Friday, killing at least 40 people and wounding more than 100, Russia’s top security agency said, according to state news agencies.

More than a third of the building, which hosts one of the largest and most popular concert halls in Moscow, was on fire on Friday night, according to Tass, as emergency services tried to rescue people from its roof.

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.