Authorities say they are actively working to identify multiple shooters following the chaos in the Five Points South neighborhood Saturday ... which left Anitra Holloman, 21; Tahj Booker, 27; Carlos McCain, 27; and Roderick Lynn Patterson Jr., 26; deceased.

The shooting took place on the sidewalk outside Hush, a popular hookah and cigar lounge ... where authorities say a vehicle pulled up next to the venue, and several shooters got out and unloaded "fully automatic" weapons on the crowd.

Per police, the culprits used "machine gun conversion devices," which make semiautomatic weapons fire more quickly.

While many bystanders were caught in the crosshairs of Saturday's shooting, police say only one person was targeted in the assault that took place not far from the University of Alabama at Birmingham.

Authorities believe this was a murder-for-hire plot ... though, the target for the attack was not identified. It's assumed one of the deceased was the intended target, however.

Birmingham Police Chief Scott Thurmond noted ... "Someone was willing to pay money to have that person killed."

Over 100 shell casings were recovered from the bloody scene ... where officers found 2 men and a woman dead. A third male gunshot victim was raced to the hospital, but later pronounced dead ... as other victims were left in critical condition.

This wasn't the only shooting Birmingham faced over the weekend ... as 3 more people were shot elsewhere in the populous Alabama city. One of the 3 victims, a man, was pronounced dead at the scene Sunday.

Mayor Randall Woodfin said it was a "priority" to get these gunmen off the streets ... calling gun violence "an epidemic" in not only Birmingham, but in the U.S., as well.

Authorities plan to speak further on the case during a news conference Monday morning.