Three victims were in critical condition and the others sustaining non-life-threatening injuries, the Denver police department said on Twitter.

The shooting occurred about 1.6km from the Ball Arena, where the Denver Nuggets defeated the Miami Heat today – ending a 47-season wait for an NBA championship – and fans crowded downtown streets afterwards to celebrate.

“Preliminary info indicates multiple shots were fired during an altercation involving several individuals,” Denver police said.

The suspect in the shooting also sustained a gunshot injury, the department added.

It was one of 290 mass shootings recorded in the US so far this year, according to the Gun Violence Archive, a non-governmental group.

Hours earlier, police said access to the city’s downtown around the arena would be limited due to road closures, and warned of big crowds and heavy road traffic.

With more firearms than inhabitants, the US has the highest rate of gun deaths of any developed country – 49,000 in 2021, up from 45,000 the year before.