“Officers located at least 15 shooting victims, including 6 who are deceased,” Sacramento police said in a statement on Twitter.

In an earlier tweet at just after 4am they had called for people to avoid the area “as a large police presence will remain and the scene remains active”.

A video posted online showed people scuffling in the street, then starting to run as gunfire can be heard. AFP could not verify the footage.

The shooting occurred in the downtown area, which has many bars and restaurants.

Police provided few other details.

It is the latest mass casualty shooting in the US, where firearms are used in approximately 40,000 deaths a year, including suicides, according to the Gun Violence Archive website.

Lax gun laws and the right to bear arms have repeatedly stymied attempts to clamp down on the number of weapons in circulation, despite greater controls being favoured by the majority of Americans.

Three-quarters of all homicides in the US are committed with guns, and the number of pistols, revolvers and other firearms sold continues to rise.

More than 23 million guns were sold in 2020 – a record – and another 20 million in 2021, according to data compiled by website Small Arms Analytics.

That number does not include “ghost” guns, which are sold disassembled, lack serial numbers, and are highly prized in criminal circles.

In June 2021, 30% of American adults said they owned at least one gun, according to a Pew survey.