The officer, Detective Sgt. Scott Biumi, is said to have been angry after having to wait for his food too long. Biumi, 48, is charged with felony aggravated assault on the customer.
Biumi will have his police certification suspended.
"He put his hand right here," said, 18-year-old Ryan Mash, the customer, pointing to his upper chest and shoulder area, "then he pulled the gun and put it, pointed it at my neck area."
Mash is a high school senior who also works at that McDonald's. He was not working that night.
A video from McDonald's surveillance shows a man in a business suit standing outside the driver's side of the vehicle that's at the drive-thru window, pulling a gun and leaning into the vehicle.
Biumi was arrested Wednesday morning and booked. He was released that afternoon on a $22,000 bond.