The incident occured earlier this week, during a Slipknot's Knotfest Roadshow's concert at the Hollywood Casino Amphitheatre in Illinois. The metal band was about an hour into their set when things took a horrible turn.

Richard Valadez, 62, was having a blast with the rest of the crowd when he suddenly collapsed.

“Basically everyone was jumping around in the mosh pit having a good time and just being friendly roughhousing dorks, as usual for metal concerts,” said witness Anthony Mackey.

Another witness told Patch that Mr. Valadez fell on the ground on at least one occasion but quickly got back onto his feet.

He was hit again later and fell out of the moshpit. Tragically, this time around proved to be too much for him.

“He seized as people were trying to help him up, so we start calling for help,” he added.

People on site tried their best to revive Mr. Valadez, including two men who reportedly performed CPR on him.

Many fans were crictical of how long it took for the staff and emergency personnel to come to his assistance.

It's been reported by NME that the metal fan was pronounced dead at the scene. However, it was later said officially that he died after being transported to a nearby hospital.

"Mr. Valadez was pronounced dead at St. James Olympia Fields Hospital on August 11 at 11:34 p.m.," said a spokewoman for the Cook County Medical Examiner's Office.

An autopsy was completed but the cause behind his death remains unknown, pending further testing, she told Patch.

Less than three weeks ago, injured fans got trampled during a Knotfest gig in San Bernardino, California. Slipknot frontman Corey Taylor stopped the show momentarily so that medics could attend to them in the moshpit and urged the crowd to get out of the way.

“No one is f**king getting hurt on my f**king watch, do you understand me?” the singer growled. “Back the f**k up!” he said in a video captured by a fan.

Taylor and the rest of the band are yet to make a comment about Mr.Valadez's passing.

This year's edition of the Knotfest Roadshow features Slipknot along with Gojira, Behemot and Volbeat. An explosive mix with plenty of moshpits ahead - if you're attending make sure you are very aware of your surroundings.