Police in the U.S. state of Alabama were looking for suspects after a weekend mass shooting killed at least four people and wounded dozens.

The shooting late Saturday night in the popular Five Points South entertainment district of Birmingham, rocking an area of restaurants and bars that is often bustling on weekend nights.

"We believe that multiple shooters fired multiple shots on a group of people" in the Five Points South district of Birmingham just after 11 p.m., police officer Truman Fitzgerald told local media.

Officers found two adult males and one adult female who was unresponsive on the sidewalk suffering from a gunshot wound, Fitzgerald said. All three were pronounced dead at the scene.

A fourth victim died at a local hospital, he added.

Dozens of people were wounded in the shooting with at least four sustaining life-threatening injuries, Fitzgerald said.

The others had "various injuries," he added.

Police have not got anyone in custody over the shooting, Fitzman said, urging the public to provide any information that could help the investigation.

"The priority is to find these shooters and get them off our streets," Birmingham Mayor Randall Woodfin said a day after the shooting.

The mayor planned a morning news conference Monday to provide updates on the case.

Several agencies are involved in the investigation, including the Federal Bureau of Investigation and the Bureau of Alcohol, Tobacco, Firearms and Explosives.

The mass shooting, one of several this year in the major city, unnerved residents and left officials at home and beyond pleading for help to both solve the crime and address the broader problem of gun violence.

This year, there have been at least 403 mass shootings – defined as a shooting involving at least four victims, dead or wounded – across the United States, according to the Gun Violence Archive.

At least 12,416 people have been killed in firearms violence this year in the United States, according to the GVA.