ALBERTA, CANADA — Josh Emard couldn't believe his eyes Tuesday when a local man dove under a slow-moving semi and was crushed to death under its rear wheels. All for a hat.

High morning winds blew the baseball hat off the man's head as he got out of his small white convertible in the parking lot of the UFA Farm Supply Store in the 2900 block of 2 Avenue North.

As the truck rolled forward, Keenan dove under to grab his hat.

The wind carried the well-worn blue-and-white hat underneath a loaded semi trailer just as it started to move.

"The truck was rolling forward, and he dove under to grab the hat. He tried to grab it and wiggle out quickly," said Emard, a fuel delivery driver for UFA.

He wondered at first if what he was seeing might just be a stunt.

"It was just unbelievable that someone would go under a moving semi for a hat."

Derek Keenan, 44, of Lethbridge died at the scene after the truck's rear wheels rolled over his upper body. The truck came to a stop with Keenan's body underneath the flatbed trailer loaded with pre-cast concrete drainage pipe.

Emard wondered at first if what he was seeing might just be a stunt.

Emard watched the incident unfold from next door at the UFA bulk fuel plant where he was preparing to leave on a delivery. He watched as the driver got out of the truck, bent down to look underneath it and then ran into the farm supply store to call for help. Then Emard ran to get help, too.

"(Josh) came running in and said 'I think a guy just got run over by that truck over there'," said Ken Hofman, who called 911 from his cellphone after running to the scene with Emard and another staff member.

"You could see he got ran over by both sets of wheels on the back of the truck," Hofman said, adding the victim didn't appear to be breathing.

Moments later, emergency medical personnel from the Lethbridge fire department arrived and tried unsuccessfully to revive Keenan.

Afterward, the 40-year-old truck driver, looking visibly shaken, was helped into an ambulance and taken to Lethbridge Regional Hospital. He's from Beiseker, located east of Airdrie.

Lethbridge police Sgt. Tom Ascroft said no charges will be laid.

"A very odd set of circumstances led to a very tragic accident," he said.