CNN
—

Four people were killed and 18 others injured when multiple gunmen opened fire in the heart of one of Birmingham, Alabama’s most popular entertainment districts on Saturday night.

Shortly after 11 p.m., “multiple gunmen fired multiple shots at a group of people” in the Five Points South area. Some of the victims were caught in the crossfire, Birmingham police said.

When officers arrived, they found two unconscious men and a woman with gunshot wounds. All three were later pronounced dead at the scene, Birmingham police Officer Truman Fitzgerald said.

A fourth victim, an adult male, was pronounced dead at the University of Alabama Hospital, according to hospital personnel.

Investigators believe the shooting was not a coincidence, but an isolated incident. Investigators are trying to find out who the target of the shooting was.

With no suspects currently in custody, Birmingham Police are working with the FBI and other agencies on the investigation. Anyone with information is urged to come forward.

The shootings join a list of at least 403 mass shootings that have occurred in the United States this year, according to the Gun Violence Archive. Like CNN, the archive defines a mass shooting as one in which at least four people are shot, not including the shooter.

There have been several mass shootings in Birmingham this year.

A shooting at a city nightclub in July left four people dead and 10 others injured, according to CNN affiliate WVRC. In February, four men were shot outside a public library, CNN affiliate WVTM reported.

Five Points South is a bustling neighborhood near the University of Alabama at Birmingham campus and downtown, known for its restaurants, nightclubs, pubs and live music venues.

The victims in Alabama were all outdoors on the sidewalk or in the street, Fitzgerald said. Investigators are trying to determine whether the shooters walked toward the victims or drove past in a vehicle, he added.

Additional gunshot victims were identified in the area and additional victims were taken to local hospitals, Fitzgerald said. The University of Alabama at Birmingham Hospital admitted 11 of the victims, including one of the deceased, Hannah Echols, a hospital spokeswoman told CNN. The victims’ conditions were not disclosed.

At least four victims suffered life-threatening injuries, Fitzgerald said.

It is unclear exactly how many people opened fire or what motivated the violence. Fitzgerald said police are investigating whether there were “multiple shots.”

Birmingham Police have asked businesses in the area to provide them with any surveillance footage they may have.

“Rest assured, we will do everything in our power to ensure that we track down, identify and bring to justice the perpetrators of the attacks on our people,” he said.

Fitzgerald said mass shootings have “more to do with culture than crime,” adding: “We see far too many conflicts decided by bullets.”

This is a developing story and will be updated.