Good evening everyone. Welcome to the readout. Jason Johnson and for Joy Reed.

Begin tonight with the breaking news out of Moscow where a shooting attack has left at least 40 dead and over 100 injured.

That's according to Russian state news agencies.

This is what we know right now.

The attack occurred at Croka City Hall, a large concert venue northwest of

Central Moscow. Morning to our viewers, we are about to show some disturbing video. You're now seeing the inside of the concert hall

where at least three men in camouflage broke in and opened fire, shooting an

unknown number of people. Russian officials say several of these gunman fired automatic weapons at the crowd.

A fire also started inside the venue.

Firefighters have evacuated about 100 people from the basement of the buildings and efforts are

underway to rescue people from the roof. Who committed this and why is still very

much unknown? Islamic State, you know ISIS, has claimed responsibility, but without providing proof for the attack

on the concert venue.

Their claim came from an ISIS-affiliated account on telegram.

NBC News has not yet verified the claim, but Russian officials said they were investigating

the attack as a terrorist attack.

Let's bring in Michael McPhall, former U.S. Ambassador to Russia, Peter Baker, Chief White House

correspondent for the New York Times, who previously worked, who previously was Moscow Bureau Chief

of the Washington Post, and former CI director John Brennan.

Thank you all gentlemen so much for joining us evening.

John, I want to start with you on this.

The idea that ISIS or someone in control of the ISIS telegram account has claimed responsibility for this.

...