DENVER (AP) -- Doughnuts were delivered Wednesday by drone to Denver's mayor and the city's police and fire departments in an event that provided a glimpse into what companies hope will be a quick, inexpensive way to get merchandise to customers.

Denver's LaMar's Donuts hired Austin, Texas-based company Drone Dispatch to deliver four boxes of doughnuts using piloted drones flown from parking lots within a block of the delivery targets.

LaMar's spokesman Tami Osifodunrin said Federal Aviation Administration regulations prohibit commercial drone pilots from losing sight of drones.

Denver Mayor Michael Hancock was outside city hall when a drone delivered doughnuts.

"This is exciting stuff and I think as we get ready for not only drones in the air, and get ready for autonomous vehicles, this is our future this is how we're going to become a more efficient 21st century nation, society quite frankly," Hancock said.

FAA officials said they were investigating to ensure the deliveries followed federal rules governing commercial drone use in populated areas. The FAA has rules that govern drone altitude, proximity to airports, and flying over people who are not part of the crew flying the drone. The organizers said they took care to comply with regulations.