A massive manhunt is underway after a horrific mass shooting rocked Birmingham with four people dead and at least 18 injured during a night of carnage at a popular cigar lounge.

A massive manhunt is underway as police search for those responsible for a mass shooting that killed four people in Alabama overnight.

Gunfire erupted in the Five Points South entertainment district outside the Hush hookah and cigar lounge in Birmingham shortly after 11pm on Saturday night, injuring at least 18 other people.

Two men and a woman were killed at the scene in the 2000 block of Magnolia Avenue, near the University of Alabama, while a fourth male victim died at the hospital.

Police believe multiple gunmen are responsible for the horrific mass shooting – but no suspects have been arrested as of Sunday morning.

The shooting is believed to have been not random but an isolated incident where several victims were caught in the crossfire.

18 other gunshot victims were identified and treated at local hospitals

Birmingham police officer Truman Fitzgerald (pictured) said the gunman either approached the victims or drove past.

Birmingham Police Department vehicles near where several people were shot Saturday night

Detectives are investigating whether the gunmen, still at large, approached the victims or drove by, Officer Truman Fitzgerald said.

“Rest assured that we will do everything in our power to uncover, identify and track down those responsible for these attacks on our people,” Fitzgerald added.

Crime Stoppers is offering a reward of up to $5,000 for information leading to an arrest. Anyone with information is asked to call the Birmingham Police Department Homicide Division directly at 205-254-1764.

Eighteen additional gunshot victims with injuries ranging from life-threatening to non-life-threatening were identified and treated at local hospitals.

The University of Alabama Hospital at Birmingham is treating 11 of the victims, hospital spokeswoman Hannah Echols told CNN.

“We have dozens of gunshot victims in this area,” Fitzgerald said. “I’m told at least four of those victims are in life-threatening condition, the others have various injuries.”

Streets in the surrounding area have been blocked off as police continue their investigation into the incident.

Witnesses described a chaotic scene as police struggled to contain the area and help victims.

Two men and a woman were killed at the scene in the 2000 block of Magnolia Avenue, near the University of Alabama, while a fourth victim died at the hospital.

Fitzgerald revealed that local authorities have contacted the FBI and ATF for assistance.

Birmingham Police have asked businesses in the area to provide any surveillance footage they may have and have asked the public to contact them with any relevant information.

Five Points South is a popular neighborhood known for its nightlife near the University of Alabama at Birmingham campus.

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

Witnesses described a chaotic scene as police struggled to contain the area and help victims.

“I came in as it was ending, because everyone was screaming, there were people crying,” Dajon Singleton told WVTM.

Police believe Glock switches were used in the shooting. These devices allow a gun to switch from semi-automatic to full-automatic mode when attached to the back of a Glock.

Gunfire erupted outside the Hush hookah and cigar lounge (pictured) in Birmingham as people waited to enter

Two men and a woman were killed at the scene in the 2000 block of Magnolia Avenue in the Five Points South neighborhood (pictured) near the University of Alabama

“Glock switches are the number one public safety issue in our city and state. While they are illegal under federal law, there is no state law that makes Glock switches illegal,” Birmingham Mayor Randall Woodfin said Sunday.

“Every mayor, police chief, sheriff, and district attorney I know wants to see Glock switches banned. Turning a semi-automatic weapon into a fully automatic weapon that unloads every bullet in seconds has no place on our American streets.”

The U.S. Attorney’s Office and the ATF have teamed up with Birmingham’s police chief and mayor to launch “Operation Flip the Switch” — a program aimed at getting Glock switchblades off the streets, WVTM reported.

“Where we used to see a dozen or less shell casings at a crime scene, we’re now seeing 75 to 100, even more than 100, at a crime scene because, as you’ll see later, these bullets are being fired very rapidly from these weapons,” said Chief Scott Thurmond.

“These weapons can do a lot of damage very quickly. As the ATF just said, there is no place for these things in our city, in our state or in our country.”

There have been more than 400 mass shootings in the United States this year, according to the Gun Violence Archive, which defines a mass shooting as an incident in which four or more people are injured or killed.

Enterprise High School and Enterprise Career & Technology Center in Alabama have been placed on lockdown after munitions were found on campus on September 5.

The lockdown followed the Apalachee bloodbath, which left nine more injured in addition to four deaths.

“Glock switches” (pictured) are modifications that turn handguns into fully automatic weapons.

Students Mason Schermerhorn and Christian Angulo, both 14, and teachers Christina Irimie, 53, and Richard Aspinwall, 39, were named as the victims.

Colt Gray, 14, the alleged shooter, has been charged with murder.

Three people were killed and at least 12 were injured in southwest Alabama after a May Day party turned violent.

Andre Reid of the Baldwin County Investigations Division told WALA-TV that about 1,000 people were attending the celebration near Stockton on May 11 when an altercation broke out and gunfire erupted.

Reid said most of the victims were “young people,” but no information was immediately available on any arrests.

“According to witnesses, the event was peaceful until an argument broke out, which led to at least one of the suspects firing several shots into the crowd,” Reid said.