The US police have seized a car after a woman was seen hanging out of its window brandishing an AK-47 assault rifle during an illegal drag race.

A photo released by police in San Francisco shows the woman, who has not been named, leaning out of a Cadillac window holding the gun as it is driven past.

Police said the photo was taken on July 11, during an "illegal exhibition of speed event" and the car was tracked down and seized on August 5.

On 7/11/2021, During an illegal exhibition of speed event at Barneveld & McKinnon, a passenger leaned out of a Cadi holding an AK47; see photo. SFPD Traffic Company personnel worked up a case, and seized this particular vehicle today. @SFPD @sfmta_muni @SFPDPerea pic.twitter.com/4disQpzziY

— SFPDTrafficSafety (@SFTrafficSafety) August 5, 2021

The incident remains under investigation.

A tweet from San Francisco police appears to show the same car being towed away while escorted by officers on motorcycles.

"Due to the fact that this is an open [and] active investigation we cannot comment further," police spokesperson Adam Lobsinger told SF Gate.

Police said they couldn't comment on whether any arrests were made, or whether the woman fired any shots.

According to the police department's mid-year report, firearm-related violence in the city during the first six months of the year has increased by 84% when compared with data for 2020, with more fatal and non-fatal shootings.