Colorado shooting: Police officer among 10 dead, one person detained at King Soopers supermarket

Ten people, including a police officer, have been killed in a shooting at a supermarket in Boulder, Colorado, officials have confirmed.

The Boulder police department responded to reports of an active shooter at a King Soopers supermarket about 2:30pm on Monday.

"We have multiple people who were killed in this incident," Boulder police commander Kerry Yamaguchi told a news briefing. "I am sorry to have to report that one of them was a Boulder police officer."

One person has been arrested, Yamaguchi confirmed.

Video shared to Twitter showed a shirtless man being escorted from the supermarket in handcuffs. His right leg appeared to be bloodied.

The man was led to an ambulance and taken to a local hospital.

"There is no ongoing public threat - we do have a person of interest in custody," Yamaguchi said, confirming the suspect was also injured during the incident.

No-one other than the suspect was seriously injured in the shooting, Yamaguchi told reporters.

"We know of no other serious injuries at this point."

The bloodshed marked the second deadly US mass shooting in a week, following gun violence last Tuesday that left eight people dead, including six Asian women, at three locations in and around Atlanta. A 21-year-old man has been charged with those killings.

Boulder police chief Maris Herold said 10 people perished in the attack at King Soopers grocery. Among them were 51-year-old police officer Eric Talley, who she said was the first to respond to the shooting near the University of Colorado's flagship campus.

Hours after reports of the shooting, Boulder police issued a second update saying officers were responding to a report of an "armed, dangerous individual" at a separate location nearby. Yamaguchi confirmed it was unrelated to the King Soopers shooting.

According to several eyewitness accounts, the shooter was wearing tactical gear and was armed with what appeared to be an AR-15 style rifle. It appears he began firing shots in the King Soopers carpark before heading inside the supermarket. 

A witness who began filming a livestream of the aftermath told NewsNOW "dozens" of shots were fired at the store. He said he saw three "lifeless" bodies on the ground, two of which were in the carpark. 

Another witness told NewsNOW the gunman was shooting "freely". She said it appeared multiple people exiting the supermarket were "limping", and one victim was taken away in a body bag.

Footage taken by a local cinematographer at the scene captured the Boulder police department issuing a warning over a loudspeaker before the alleged suspect was detained.

"The entire building is surrounded. You need to surrender.

"Come out with your hands up, unarmed. This is the Boulder police department," an officer said.

In a statement, Colorado Governor Jared Polis described the shooting as a "tragedy".

"Like my fellow Coloradans, I am closely watching unfolding events at King Soopers in Boulder. My prayers are with our fellow Coloradans in this time of sadness and grief as we learn more about the extent of the tragedy," he said.

The FBI said on Twitter its agents were assisting local police in the investigation of the supermarket shooting. 

Reuters / Newshub.