Four people were killed and dozens injured in a shooting in Birmingham, Alabama, on Saturday night.

Police said officers responded to reports of a major shooting. "Officers are on the scene of multiple people shot with possibly multiple casualties," the Birmingham Police Department wrote in a post to X.

The shooting occurred in the Five Points South area of the city, the post added.

ABC News Birmingham affiliate WBMA reported that at least four people were killed and dozens injured in the shooting. At least four of the injured have life-threatening injuries, WBMA said.

WBMA said the shooting occurred around 11 p.m. Saturday night in the busy Five Points South area.

Three of the four victims died on the scene, WBMA said. The fourth victim died at the hospital.

Investigators said they made no arrests and believe there were multiple shooters. Police are investigating whether a gun fitted with a so-called "switch" -- which allows a semi-automatic weapon to fire at a faster rate -- was used in the shooting, WBMA said.

The Birmingham Police Department has requested FBI and ATF assistance with the investigation, WBMA reported. Authorities are also seeking information from witnesses.

"There is no greater resource than the public," Birmingham Police Officer Truman Fitzgerald said. "We will do everything we possibly can to make sure we uncover, identify and hunt down whoever is responsible for preying on our people this morning."

This is a developing story. Please check back for updates.

ABC News' Jessica Gorman contributed to this report.