A heroic security guard has been caught on camera shooting a bank robber dead after the criminal threatened customers and tellers with a gun.

Serial armed robber Laurence Turner, 34, walked into Alpine Bank in Rockford, Illinois, armed with a gun and wearing a ski mask.

As he pointed his pistol at staff behind the counter, Brian Harrison whipped out his gun and shot the criminal dead - all of which was caught on security footage.

Laurence Turner, 34, is pictured entering the bank firing his gun at the ceiling wearing a blue ski mask

As two tellers cower behind the counter, Brian Harrison draws his gun and shoots the robber

Harrison fires the gun as the robber scrambles for the door. Staff are seen hiding behind the counters

Laurence Turner was shot dead inside a bank

The incident occurred on January 20, and the hero security guard had been sweating over whether or not charges would be brought against him.

But Winnebago County State Attorney Joe Bruscato confirmed yesterday that he acted in self-defense and in the defense of others and will therefore face no charges.

Footage from the bank captures Turner getting out of his car covering his face and carrying a bag.

He fires at the ceiling before aiming his gun at Mr Harrison, who is a retired Winnebago County Sheriff's Department deputy.

A security camera from another angle shows the robber entering the bank and staff ducking behind the counter

The robber fires at the ceiling before aiming his gun at Mr Harrison, who is a retired Winnebago County Sheriff's Department deputy

The security guard draws his gun and shoots around the front of the counter at a cowering Turner, who tries to flee but falls to the ground by the door

Pictured above left the mask donned by the robber and, right, the bag he carried hoping to stash some cash

The security guard draws his gun and shoots around the front of the counter at a cowering Turner, who tries to flee but falls to the ground by the door.

He was shot in his chest and his buttocks.

Gloves worn by the robber are seen above

Turner had stolen his mother's Hyundai Santa Fe on the morning of the robbery, which was at least his fourth in three months.

He held up Mincemoyer Jewelers on November 23 to steal a laptop, Harvard State Bank five days later when cash was taken and Members Alliance Credit Union on December 16 when he took money again by brandishing a gun.

An autopsy showed Turner had opiates, THC and cannabis in his system, Bruscato told the RR Star.

In a letter to the Star's editor in the aftermath of the incident, the bank said Mr Harrison had 'acted with courage and quickness to protect our family. You are a hero to each and every one of us'.

From another angle the robber is seen entering the bank above. He was later identified as Turner

An autopsy showed Turner had opiates, THC and cannabis in his system