Crocus City Hall

There was a shooting ongoing at the Crocus City Hall, a music venue in Moscow. At least three gunmen were killing people. There are videos of it circulating online.

The U.S. embassy in Russia warned that 'extremists' had imminent plans for an attack in Moscow, hours after Russian security services said they had foiled a planned shooting at a synagogue by a cell from the Afghan arm of Islamic State."

US warning

Update: The theatre now appears to be on fire.