As Russia mourns victims of concert hall shooting, how will Putin react?

Moscow's New Arbat Avenue is lined with some of the biggest video screens in Russia.

Today they're all displaying the same giant image: a burning candle and the Russian word "Skorbim" ("We mourn.")

Russia is mourning the victims of the Crocus City Hall massacre. There is no final death toll. The search for bodies continues.

Across the country the Russian tricolour is flying at half mast, entertainment and sports events have been cancelled, TV newsreaders are wearing black.

It might not be in the centre of Moscow, but Crocus City Hall is one of the most prominent music venues in Russia.

But Friday's bloodbath turned a concert hall into hell. The attackers killed not only with bullets, but with fire. They set the building alight and created an inferno. Video released by Russia's Investigative Committee shows that the roof collapsed. Metal beams, too.

Outside the building the police lines are still in place. From where I'm standing, I can see a single burned-out section of the entertainment complex. It's a hint of the devastation inside.

People are queuing to lay flowers at a makeshift shrine to the victims of the atrocity. The mountain of tributes is growing ever larger. As well as leaving roses and carnations here, visitors are placing dolls and soft toys on the flowers. That's because among the dead were children.

People have been leaving messages, too. One is addressed to the attackers:

Among the crowd here there is a mixture of grief and anger.

"The country's heart is aching," says Tatyana, who's brought some flowers to lay here. "My soul is crying. Russia is crying. So many young people were killed. It feels as if my own children have died."

"It was a big shock," says Roman. "I live nearby, and I saw what happened from my window. It's horrific and a big tragedy."