A mass shooting killed four people and wounded 18 others in a popular nightlife area in Birmingham, Alabama, with many of the victims caught in the crossfire, police said early Sunday. Authorities asked the public for tips as they searched for the shooters.

The shooting happened shortly after 11 p.m. Saturday in Five Points South, a district filled with entertainment venues, restaurants and bars that is often crowded on weekend nights.

Multiple suspects pulled up in a vehicle, got out, fired shots, got back in the vehicle and fled, Police Chief Scott Thurmond said at a news conference Sunday morning. He described the shooting as possibly 鈥渁 hit鈥� conducted in exchange for payment.

Officers found two men and a woman on a sidewalk with gunshot wounds, and they were pronounced dead there. An additional male gunshot victim was pronounced dead at a hospital, police said.

Authorities believe the intended target was among the dead, Thurmond said at the news conference, where he was joined by Mayor Randall Woodfin and officials from the FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives. Investigators believe other victims were caught in the crossfire.

By early Sunday, after victims began showing up at hospitals, police had identified 18 people with injuries, some of them life-threatening, Officer Truman Fitzgerald said in an email.

There were no immediate arrests. Anyone with information was asked to contact authorities.