One teen is dead and two others, including a 12-year-old girl, have been injured following a shooting at an Alabama mall prior to Black Friday shopping.

Authorities say the shooting happened about 9:30pm on Thursday at the Riverchase Galleria in Hoover, the largest mall in Alabama, as thousands were getting ready to stock up on Black Friday sales.

Witnesses and police who arrived on the scene described the scene as chaotic, as gunshots sent the crowd into panic.

Lexi Joiner, who was shopping with her mother when the gunfire erupted on the mall’s second floor said she heard six or seven shots ring out and was ordered, along with other nearby shoppers, into a supply closet for cover.

“It was terrifying,’’ Joiner told AL.com.

A high school senior, who decided to get involved in Black Friday for the first time, described how tires were squealing in the carpark as people tried to flee.

“I knew it would be crazy, just not this crazy,” he told AL.com.

Other shoppers in the centre were then seen with their guns drawn, the publication reported.

Police say the incident started with a physical altercation between an 18-year-old and the 21-year-old gunman.

The gunman tried to flee but was confronted by two Hoover police officers.

Captain Gregg Rector said at a news conference that a Hoover officer “did engage that individual, shot him and he is dead on the scene.”

The second teen was hospitalised in serious condition.

Mr Rector said a 12-year-old girl also struck by gunfire was hospitalised. Her condition was not immediately known.