Police in California are still searching for at least two people who opened fire on the outskirts of Sacramento’s entertainment district – killing six and injuring 12.

The latest US mass shooting happened at around 2am on Sunday.

Police chief Kathy Lester revealed few details about the investigation but pleaded with the public to share videos and other evidence that could lead to the gunmen.

“The scale of violence that just happened in our city is unprecedented during my 27 years here,” she told reporters during a press conference.

“We are shocked and heartbroken by this tragedy, but we are also resolved as an agency to find those responsible and to secure justice for the victims and the families.”

Small memorials with candles, balloons and flowers were placed near the crime scene on Monday morning.

One balloon had a message on it saying: “You will forever be in our hearts and thoughts. Nothing will ever be the same.”

Streets were reopened to car and foot traffic and police tape was removed. Aside from a handful of TV cameras, there was little sign of the previous day’s bloodshed.

Sacramento mayor Darrell Steinberg and other city officials decried escalating violence in the city while also urging people to keep coming downtown for events like professional basketball games and performances of the Broadway musical Wicked.

“We can never accept it as normal and we never will,” Mr Steinberg said of the shooting. “But we also have to live our lives.”

The gunfire erupted just after a fight broke out on a street lined with an upscale hotel, nightclubs and bars, and police said they are investigating whether the row is connected to the shooting.

Video from witnesses posted on social media show rapid gunfire for at least 45 seconds as people scream and run for cover.

The shots startled sleeping guests at the Citizen Hotel, which had hosted a wedding party and fans of rapper Tyler the Creator, who had performed at a concert hours earlier.

From her window on the fourth floor, 18-year-old Kelsey Schar said she saw a man running while firing a gun. She could see flashes from the weapon in the darkness as people ran for cover.

Sacramento mass shootingSacramento police crime scene investigators place evidence markers on the street (Jose Carlos Fajardo/Bay Area News Group/AP)

Ms Schar’s friend, Madalyn Woodward, said she saw a girl who appeared to have been shot in the arm lying on the ground.

Security guards from a nearby nightclub rushed to help the girl with what looked like napkins to try to stem the bleeding.

Police found a stolen pistol and are investigating if it was used in the shooting.

The dead include three men and three women.

The women were identified as Johntaya Alexander, 21, Melinda Davis, 57, and Yamile Martinez-Andrade, 21, while the men were named as Sergio Harris, 38, Joshua Hoye-Lucchesi, 32, and Devazia Turner, 29.

Of the 12 hurt, at least four had critical injuries, according to the Sacramento Fire Department.

Sacramento Mass ShootingThe scene of the mass shooting In Sacramento (Rich Pedroncelli/AP)

Sunday’s violence is the third time in the US this year at least six people have been killed in a mass shooting, according to a database compiled by the Associated Press, USA Today and Northeastern University.

It is the second mass shooting in Sacramento in the last five weeks.

US President Joe Biden called for action on gun crimes in a statement on Sunday.

“Today, America once again mourns for another community devastated by gun violence,” he said. “But we must do more than mourn; we must act.”

On February 28, a father killed his three daughters, a chaperone and himself in a Sacramento church during a weekly supervised visitation.

David Mora, 39, was armed with a homemade semi-automatic rifle-style weapon, even though he was under a restraining order that banned him from having a firearm.