Police in Colorado said they are responding to an active shooter at a supermarket. It's unclear if anyone has been injured.
Police in Boulder tweeted on Monday that the shooter is at a King Soopers grocery store.
A shirtless man with blood running down his leg was escorted out of the store in handcuffs by two police officers, a live TV feed showed.
Television helicopter video showed many law enforcement vehicles and officers outside the store and at least three helicopters on the building's roof.
Law enforcement SWAT teams from Jefferson County and Boulder were dispatched to the market in the southern part of the city of Boulder. Aerial footage showed several medical evacuation helicopters landing in the area.
The windows of the store appear to be broken, according to a bystander live video on YouTube. (AP) DIV DIV