A group of drone operators whose stunts over the Alex Fraser Bridge sparked two separate investigations last month is facing a potential fine of up to $25,000, CTV News has learned.

Members of Rotor Riot sent a drone zooming up and down the towers of the busy crossing back in October, then uploaded the video to their YouTube page. 

Both the Delta Police Department and Transport Canada launched investigations into the stunts, and on Friday the group said it is facing a stiff penalty in the tens of thousands of dollars. 

Though the video shows a steady stream of cars and trucks crossing the Alex Fraser, Rotor Riot founder Chad Kapper insists they never actually flew the drone over any vehicles.

"I would never recommend people flying over crowds of people or traffic or any place where a mistake is going to make it very dangerous," Kapper told CTV News from Ohio.

Rotor Riot believes its operators were being safe, but local drone experts and police disagree.

Rob Brooks of Candrone, which runs courses on unmanned aerial vehicle use, said the drone in the video was flown too close to cars. He also suggested the operators were breaking the rules by using first-person view goggles to pilot the device.

"Technically their drone is not within the line of sight, so that is a direct violation," Brooks said.

Delta police also feared that if the group had lost control of the drone, it could have plummeted down into a vehicle, potentially triggering a chain reaction crash on the bridge.

Kapper told CTV News the group's pilots are seasoned professionals, and have learned to fly in different climates and conditions all over the world. He did say he is concerned about less-skilled copycats trying to emulate their stunts.

"Always that possibility," Kapper said. "Am I concerned about it? Yeah, to a certain extent, but you can only do so much."

Transport Canada considers YouTube videos like Rotor Riot's to be a commercial operation, meaning they face heaving fines and are subject to stricter rules than recreational users.

The maximum fine faced by hobbyists is $3,000.

With files from CTV Vancouver's Penny Daflos