At least 40 people have been killed and 145 wounded, in the worst terror attack in Russia in years, as gunmen in combat fatigues opened fire and detonated explosives in a major concert hall on the outskirts of Moscow. Islamic State claimed responsibility for the attack late on Friday, in a post on Telegram in which the group claimed its gunmen had managed to escape afterwards. A US official said Washington had intelligence confirming Islamic State’s claim. Photos showed the Crocus City Hall engulfed in flames as videos emerged showing at least four gunmen opening fire with automatic weapons as panicked Russians fled for their lives. In one clip, three men in fatigues carrying rifles fired at point-blank range into bodies strewn about the lobby of the concert hall. Children were reportedly among the victims of the attack, in which the assailants also apparently detonated explosives. At least two blasts took place at the concert hall on Friday evening, news agencies reported. By late evening, Russian authorities had launched a mass manhunt for the gunmen in the attack, warning residents in Moscow and its suburbs to look out for signs of the attackers. The Russian government did not immediately identify any of the suspects. Video published online showed horrific scenes of some people begging for help from the roof of the concert hall as it burned behind them. Other video footage showed people screaming, crawling on their hands and knees out of the music venue or fleeing down stairwells. One witness said he was about to settle into his seat when he heard “several machine gun bursts” and “a lot of screams”. “I realised right away that it was automatic gunfire and understood that most likely it’s the worst: a terrorist attack,” the man, who gave his name as Alexei, told AFP. Another concertgoer described scenes of panic as terrified people tried to escape. “A stampede began. Everyone ran to the escalator,” he told Reuters. “Everyone was screaming; everyone was running.” At least three emergency helicopters had been deployed to extinguish the fire. There had been a partial collapse of the roof of the Crocus City Mall, local media reported. Moscow mayor Sergei Sobyanin said that the Moscow government would cancel all cultural, sporting and other mass events for the weekend after the attack, as the Russian railways and other major utilities said they were increasing security. Sobyanin called the attack a “great tragedy”. At least 70 ambulances had been dispatched to the site of the attack. Earlier this month, western countries led by the US had issued terror warnings and told their citizens not to join public gatherings in Russia. On 8 March, the embassy wrote it was “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”. Russian media reports said riot police units were sent to the area as people were being evacuated and Speznaz units of the Russian national guard began storming the building later on Friday evening. Some of the attackers may have escaped, the Russian news agency Baza reported. The shootings at the concert hall were reminiscent of some of Europe’s worst terrorist incidents such as the attack on the Bataclan in Paris in November 2015. Russians are likely to recall the Nord Ost terrorist attack in Moscow in 2002, when gunmen took hostages at a theatre in one of the worst incidents in the country’s history. The British embassy in Moscow condemned Friday’s attack. “We condemn the terrorist attack at the Moscow region’s Crocus City Hall. It’s a horrible tragedy. We offer sincere condolences to the relatives and loved ones of those hurt and killed in today’s events,” the embassy said in a statement on its Telegram channel. White House national security spokesperson John Kirby said the “images of the attack were just horrible and just hard to watch”. The White House had no indication that Ukraine was involved in the attack, Kirby added. Russia is fighting a major war in Ukraine. Yulia Navalnaya, the wife of late Russian opposition leader Alexei Navalny, who died in February in a Russian penal colony, described the attack as a “nightmare”, adding in a post on X: “Condolences to the families of the victims and recovery to the injured. All those involved in this crime must be found and held accountable.” An eyewitness told the Mash Telegram channel that there were “at least five” attackers and that they were “bearded”. “They act like trained fighters,” the account read. “At the moment of entering the building, the guards and people standing at the door were killed. Then they blocked the main entrance. “The terrorists are armed with [Kalashnikov] assault rifles. Some carried vests with various ammunition. At least two of the attackers are carrying backpacks, possibly with molotov cocktails.” A top Ukrainian official said the country had no involvement in the attack. “Ukraine certainly has nothing to do with the shooting/explosions in the Crocus City Hall,” Mykhailo Podolyak, an adviser to the Ukrainian presidential administration, wrote on X. “It makes no sense whatsoever. Ukraine has never resorted to the use of terrorist methods.” Dmitry Medvedev, the ex-president of Russia and now deputy chairman of its security council, wrote that “if it is established that they are terrorists of the Kyiv regime, it’s impossible to treat them and those who inspired them differently. “They all should be found and relentlessly destroyed as terrorists. Including officials of the state that committed such an evil thing. Death for death.” There was no evidence that Ukraine had any involvement in the attacks. The attack took place at a sold-out concert by the Russian rock band Piknik. Crocus City Hall is one of the largest and most popular music venues in the Moscow oblast. The warnings from the western embassies came shortly after Russia said it had foiled a planned shooting by an Afghan group linked to Islamic State. Russian authorities had recently carried out a series of raids against armed Islamist militants in the region of Ingushetia, leading to pitched firefights between police and the fighters. It was unclear if this was the attack referred to in the warning. Russian leader Vladimir Putin had called the March warnings from western embassies a “provocation”. “All this resembles outright blackmail and the intention to intimidate and destabilise our society,” he said earlier this month. Russia has not faced a large terrorist attack on its own territory since 2017, when 14 people were killed in a blast on the St Petersburg metro. Suicide bombers killed 34 people in Volgograd in 2013 shortly before the Sochi Olympics. And in 2011, suicide bombers killed 30 people at Moscow’s Domodedovo airport.