A Frontier Airlines plane was evacuated after staff found a gun magazine aboard in Denver — days after a flight struck and killed a trespasser on the tarmac at the same airport.

Passengers deplaned from a Frontier flight from Denver to Phoenix on Sunday after staff made the startling discovery, a company spokesperson confirmed.

Passengers were screened “as a matter of precaution,” and no actual firearms were found aboard.

“Our preliminary investigation indicates that the magazine belongs to a law enforcement officer,” Frontier told The Post.

It was the fourth chilling airport safety episode in a week.

The trespasser was struck and killed by the plane on the runway and passengers reported seeing his severed legs swirling around in one of the engines.

A day before that, a Delta Airlines employee died when a towing vehicle crashed into a passenger boarding bridge in Orlando.

A United plane hit a highway truck while coming in for a landing at Newark International Airport on May 3.

Passengers on Sunday’s evacuated Frontier flight were rebooked for a Monday flight, but the airline refused to give refunds to passengers seeking to cancel, ABC 7 reported.

“The Frontier gate attendant just told us that it was not Frontier’s fault, and they couldn’t be held responsible,” passenger Rashon Hammonds told the outlet, adding that he didn’t get any compensation save a $15 refund voucher.