Washington, Mar 23 (IANS): At least 10 people, including a police officer, were killed when a gunman opened fire at a grocery store in the US state of Colorado, authorities said, adding that a suspect was in custody.

The shooting took place on Monday in the city of Boulder.

According to a BBC news report, the incident began around 2.30 p.m. when the suspect entered the King Soopers grocery store and began firing.

Then at about 2.50 p.m., the Boulder Police Department tweeted an alert about an "active shooter" at the store.

Police said officers arrived at the scene "within minutes" of receiving a 911 call and entered the building "very quickly".

Two hours later, the police again warned people to avoid the area, the BBC reported.

"Do not broadcast on social media any tactical information you might see," the tweet added.

However, the shooting was live-streamed by witnesses and broadcast on YouTube.

After the incident, the Department confirmed that a person of interest was in custody and there was "no ongoing public threat", dpa news agency reported.

The man was injured and was being treated.

Police said that more information would be released "as facts are confirmed", adding the only known injured person was the suspect.

In a tweet, Colorado Governor Jared Polis said: "My prayers are with our fellow Coloradans in this time of sadness and grief as we learn more about the extent of the tragedy."

The White House confirmed that President Joe Biden has been briefed about the carnage.