Russian media reports, citing Russian security services, say gunmen have attacked a concert hall in the Russian city of Krasnogorsk, Moscow oblast on the evening of March 22.
Attackers clad in camouflage gear reportedly took part in the attack, in the north-western suburb of Krasnogorsk.
Four men directly involved were among 11 arrested on Saturday, Russian security officials say.
Crocus City Hall was about to host a rock concert when the gunmen burst into the foyer and then the theatre itself.
More than 6,000 Russians had flocked to the Crocus City Hall retail and concert complex for a concert by rock group Picnic.
Fire and plumes of smoke rose into the sky and the hall's facade burst into flames as glass on the top two floors of the building blew out. The fire appeared to have started when the attackers threw some kind of incendiary device. Much of the building was engulfed by fire and part of the roof collapsed.
Children are said to be among the casualties and the Russian foreign ministry has condemned a "terrorist attack". Russian Foreign Ministry spokeswoman Maria Zakharova called on the international community to condemn the incident, calling it "a monstrous crime".
The Islamic State (IS) terrorist group said it was behind the attack. ABC News reported on March 23 that in a statement posted by Amaq news agency, which is linked to the IS terrorist group, the IS's Afghanistan affiliate said it had attacked a large gathering of “Christians” in Krasnogorsk.
US officials told CBS, the BBC's partner service in the US, that it had obtained intelligence that showed IS had wanted to attack Russia. According to the BBC, the White House said it had warned Russia earlier this month of plans for a potential attack in Moscow targeting “large gatherings”.
Two weeks ago, the US embassy reportedly put out a warning to US citizens to avoid large gatherings, saying it was monitoring reports that “extremists have imminent plans to target large gatherings in Moscow.” It updated its advice on Friday evening, urging US citizens to avoid the vicinity of the attack.
Ukraine's government was quick to deny any involvement in the attack, which comes more than two years after Russia launched the so-called “special military operation” in Ukraine.
The March 22 attack was the worst targeting civilians in Moscow and Moscow oblast for years.
Sputinik reported on March 24 that all four suspects apprehended are citizens of Tajikistan, reportedly registered in the Yaroslavl, Ivanovo and Samara regions. None of them have a Russian passport.
“Three of the four detainees do not speak Russian fluently. The fourth, not at all; he had to be interrogated through an interpreter,” Sputnik said, noting that the suspects lived together in a hostel in the north of Moscow for close to a month before the terrorist attack.
According to Sputnik, one of the suspects named Faridoun Shamsuddin claims he carried out the terrorist attack “for money” after a man “without a name or surname” contacted him via Telegram a month ago.
The handler, who referred to himself as a “preacher’s assistant”, reportedly asked Shamsuddin to “kill people, no matter who.”
Shamsutdin was promised “half a million rubles” for the killings of which half was transferred to his card.
