A gunman has opened fire outside a US nightclub, killing at least one person and injuring 15, according to local media reports.

Police were called to a shooting around 11.30pm in Kansas City in Missouri, ABC News have said.

The suspect fired into a queue of people waiting to get into a bar, according to a police spokesperson, who said the motive remains unclear.

Police said they found a woman and a man dead in the car park following a “chaotic scene”.

An armed security guard is believed to have stopped the gunman, who is believed to be one of the dead, according to police.

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“No police officers fired any shots in this incident,” the spokesperson told local media.

He said three victims remain in critical condition following the attack.

A Kansas City Police spokesperson said there have been no reports of any arrests.

Local station KSHB-TV said people were shot outside the bar 9ine Ultra Lounge.

A Facebook post on the club's page advertised Sunday night's "Sold Out Sundays" event, which appeared to be a celebration of the Kansas City Chiefs, who beat the Tennessee Titans on Sunday to advance to the Super Bowl.

"It is hard to stand here and talk about this tragedy on really one of the best days Kansas City has had in a long time," Jean Peters Baker, the county prosecutor, told reporters.