A man in the US state of Oregon said he was grateful to be alive after he narrowly escaped – by mere seconds – from being hit by a runaway circular saw blade that had come loose from a nearby construction site and hurtled towards him.

Mr Shane Reimche was not aware that the blade was spinning towards his back until after he entered a convenience store and closed the door.

“I was walking into the store and I was pulling the door handle (behind me). I heard a loud bang and yelling,” he told local news outlet Kezi 9 News, adding that he turned to see a cloud of smoke, a man falling into a ditch outside, “and a four-foot blade hurtling at me”.

The incident happened in the town of Eugene on March 28.

In a video from closed-circuit television camera footage widely shared on social media, Mr Reimche walks into the convenience store. As the door closes behind him, the saw blade can be seen spinning at high speed across the car park in front of the store before it hits the door frame.

Mr Reimche said: “Obviously it wasn’t my time, but closest I’ve ever experienced.”

The store’s owner, Mr Amit Grewal, said the impact of the saw blade against the door frame was so powerful that it shook the entire store.

He said: “We were standing behind the counter. All I heard was metal rolling down the street. All of a sudden we heard a loud bang, it shook the whole store.”

An eyewitness told Kezi 9 News that the saw blade might have come loose because of a lost bolt as well as possible operator error.

Mr Reimche said: “I had tears all night. It was petrifying. I was shaking in the store. Took a little while before I could talk. That thing was huge – you can see the hole in the wall.

“I don’t think I would’ve survived being touched by that thing.”