DENVER — A Lyft driver who was on his way to pick up a passenger was allegedly sucker punched and knocked out near downtown Denver earlier this month.

Robert Cleveland told FOX31 he was driving on Walnut Street and heading toward 27th Street in the River North neighborhood when he saw about a dozen Honda Grom riders.

“I didn’t think anything of it until I saw them start doing stunts,” Cleveland said.

That’s when he pulled out his cellphone and started recording.

He said the riders were blocking traffic and wouldn’t let him pass.

Then when he reached 27th Street, Cleveland said he’d had enough.

Video from someone who was in the area shows Cleveland braking hard. Then, he got out of his car and confronted the riders, who had gotten off their motorcycles.

“At that moment, I didn’t think anything of it, mainly because I’m a pretty big dude,” Cleveland said.

Cleveland is 6 feet 7 inches tall and weighs about 245 pounds. He’s spent years as a bartender and said he’s comfortable defending himself.

Video shows Cleveland talking to one of the riders, when another one who’s on his right sucker punched him.

“I was talking to the guy and all of a sudden, from my right side, I got blindsided…didn’t see the guy hit me. And that’s all I remember,” Cleveland said.

He was knocked out for about 10 minutes and woke up to paramedics helping him.

Cleveland said the punch gave him a concussion and cracked his orbital. He said the riders did about $500 in damage to his car and stole a smartphone and dashboard camera.

“When I reflect on that, I probably should’ve done that (called police),” Cleveland said. “But in the heat of the moment, with everything that’s happening… someone kicking your car, pushing the issue… I had had enough.”

If you recognize the riders or know anything about the punch, you’re asked to contact FOX31’s partners, Metro Denver Crime Stoppers, at: 720-913-7867. You can remain anonymous and could receive a reward.