21 people shot by multiple gunmen on Birmingham street, police say

Four people were killed and at least 17 others injured in a shooting in Birmingham, Alabama, on Saturday night, police said.

Birmingham Police said Sunday night that Anitra Holloman, 21, of Bessemer; Tahj Booker, 27, of Birmingham; and Carlos McCain, 27, of Birmingham, were three of the four victims killed in the incident.

The shooting -- which occurred just after 11 p.m. in the 2000 Block of Magnolia Avenue South, in the Five Points South Entertainment District -- was "not random and stemmed from an isolated incident where multiple victims were caught in the cross fire," police said in a statement.

Police are seeking multiple suspects who they said "fired upon a large group of people who were outside in a public area" and then fled the scene in a vehicle.

"Officers arrived on the scene when they observed two adult males and one adult female lying unresponsive on a sidewalk suffering from multiple gunshot wounds," police said. All three victims were pronounced dead at the scene by Birmingham Fire and Rescue personnel.

Additional victims were then located in the area, while others began arriving at local hospitals. One man was pronounced dead at UAB Hospital, police said.

As of Sunday morning, police said there were a total of 21 gunshot victims -- four dead and 17 wounded, "with injuries ranging from non-life-threatening to life-threatening."

During a press conference Sunday morning, police said they believe it was a "targeted shooting," and that the targeted individual was among those who are dead. They did not identify the person or say why they might have been targeted.

Birmingham Police Chief Scott Thurmond extended "heartfelt condolences" to the victims and their families.

"Our hearts go out to them as we work through this," Thurmond said.

Mayor Randall Woodfin called for an end to gun violence, saying his "first priority is public safety."

"Do not tell me this is not solvable -- at the same time, do not tell me this is only on the police to solve it," Woodfin said. "Elected officials -- locally, statewide and nationally -- have a duty to solve this American crisis, this American epidemic of gun violence."

More than 100 shell casings were collected at the scene, and police said they believe a modified weapon with a "gun switch" may have been used in the incident.

"We believe that the firearms that were used have been converted to fully automatic," Thurmond told Phil Lipof on "ABC News Live Weekend" on Sunday.

No arrests have been made as of Sunday morning.

The police urged anyone with information on the shooting to contact the BPD Homicide Division at 205-254-1764 or anonymously via Crime Stoppers at 205-254-7777. Crime Stoppers may award tipsters up to $5,000 in cash for information, the police added.

The Birmingham Police Department is working with the FBI and ATF on the investigation, the department said. Authorities are also seeking information from witnesses.

ABC News' Jessica Gorman and Darren Reynolds contributed to this report.