Ten people, including a police officer, were killed during a hours-long attack carried out by a gunman at a grocery market in Colorado, reported foreign media.

The shooting was live-streamed by witnesses and broadcasted on YouTube.

The incident had begun when the suspect had entered the King Soopers market and began firing, which was followed by a Twitter message by the Boulder police, noting that there was an "Active Shooter at the King Soopers on Table Mesa" street.

Two hours later, the police warned the public to avoid the area, noting, "Do NOT broadcast on social media any tactical information you might see"

However, footage of the stand-off of captured by a camera by a passer-by showing victims near the grocery store.

The attack ended with the gunman, injured and shirtless was led away by the authorities.

Speaking in this regard, Colorado Governor Jared Polis stated, "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 stated that US President Joe Biden was briefed regarding the incident