At least nine people have been injured in a mass shooting in Denver, police said.

It appears multiple shots were fired during an altercation involving several people in the 2000 block of Market Street, the Denver Police Department said on Twitter.

Of the nine people shot, three were in critical condition and the rest are believed to have non-life-threatening injuries, police said. A suspect in the shooting was also shot.

The shooting happened hours after the Denver Nuggets won their first NBA championship Monday night in Denver, but it's unclear whether the shooting is connected to celebrations in the city.

Police said they are conducting a "complex investigation."

The violence near downtown Denver is one of at least 290 mass shootings in the US so far this year, according to the Gun Violence Archive, which like CNN, defines a mass shooting as one in which four or more people are shot, excluding the shooter.

This is a developing story and will be updated.