40 fans reportedly killed in rock concert mass shooting in Moscow

At least 40 people have been killed and more than 100 wounded at a Moscow show by Russian art-rockers Picnic. According to reports, gunmen dressed in combat fatigues opened fire on the crowd at the 7300-capacity Crocus City Hall, before detonating explosives and setting the building on fire. The band had not yet taken the stage. 

In a situation that is still developing, at least five gunmen are barricaded in the building, while news agency video footage suggests that the roof has collapsed. 

No one has yet claimed responsibility for the attack, which comes two weeks after the UK and US embassies in Moscow issued warnings about extremist plans to target large gatherings in the city, including concerts, and less than a week after Russian presidential elections resulted in Vladimir Putin winning a fifth term in office. 

Russian prosecutors have called the attack "an act of terrorism" and have opened a criminal case, while Russian Foreign Minister Maria Zakharova has called the attack a "monstrous crime" and urged the international community to condemn the action. 

Former Russian president Dmitry Medvedev has issued a statement on instant messaging service Telegram calling for action. "Terrorists understand only reciprocal terror," he wrote. "No trials or investigations will help if force is not answered with force, and deaths with total punishment of terrorists and repression of their families. That’s our worldly experience.

"If it can be established that these terrorists were from the Kyiv regime, it’s impossible to deal with them and those who have been inspired by their ideology any other way. They must all be found and ruthlessly destroyed as terrorists. Including official representatives of the state that committed such an atrocity."

"There's no indication at this time that Ukraine or Ukrainians were involved in the shooting," White House national security spokesperson John Kirby told reporters. "We're taking a look at it, but I would disabuse you at this early hour of any connection to Ukraine."

Earlier this month, Russia's Federal Security Service (FSB) said that it had prevented an attack on a synagogue in Moscow being plotted by Wilayat Khorasan, a cell of the Islamic State based in Afghanistan.

Moscow's mayor has cancelled all large-scale public events scheduled to take place over the weekend.

In November 2014, 90 fans were killed during a show by Eagles Of Death Metal at the Bataclan venue in Paris, during a series of coordinated terror attacks.