An armed bystander has shot a man suspected of opening fire at a back-to-school rally in Florida.

The event, called Peace in the City, was taking place at Isaac Campbell Park, in Titusville and featured several games and gifts of school supplies for approximately 150 children and their families, none of whom appeared to be hurt.

Titusville Police Deputy Chief Todd Hutchinson said in a statement: “This suspect opened fire at a crowded public park, this could have been so much worse.” The gunman is believed to have fired at least 12 bullets into the crowd according to police.

A video posted by the DJ at the event, Dwight Harvey, showed the moment the shots rang out.

He said at the tail end of the mobile footage: “Y’all just witnessed a live shootout”.

Mr Harvey told reporters on the scene “there were kids in the path of those bullets. Thank God none of the kids got hit. To have this happen at an event for the kids, at the ‘Peace in the City’ rally, is just crazy to me. It’s unbelievable. It hurts”.

The suspected shooter took a bullet to the head and was airlifted to a local hospital with life-threatening injuries, according to police.

According to local news station WFTV, a grudge may have been involved, with the suspect having had reportedly fought with one of the rally attendees over a basketball game three weeks prior.

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The legally-armed bystander, who remains unidentified, confronted the suspect before shooting him in the head.

Police said the bystander cooperated with authorities and no charges have been filed against him.

As the national debate over gun control reform continues in light of deadly school shootings, the National Rifle Association (NRA) was quick to jump on the news of the bystander.

The organisation tweeted the day after the park shooting: “this is another example of a good guy with a gun stopping a bad one”.