WATCH: Thousands Remember 9/11 with OC-LB Ride

Thousands of bikers gathered today for a motorcycle and fire engine ride in remembrance of 9/11, starting at Cook's Corner near Lake Forest, and winding through numerous Orange County communities where spectators cheered riders on.

The riders, some repeat visitors to the parade, some first-timeers, revved up in the afternoon as part of a parade organized by Long Beach Firefighter Gary Biggerstaff, who has attracted help and support from all over Southern California and beyond.

About two hours after their start, a stream of motorcycle riders flowed into the parking lot and streets surrounding Los Alamitos Landing in Long Beach near the Seal Beach border.

Most people were smiling and celebratory in a nobody's-gonna-stop-us-from-living-life mood. Some riders were more somber and emotional. The crowd burst into applause with the arrival and fly-over of the three-plane, missing man formation in the sky, which was visibile for miles.

Biggerstaff was changed, he says, by visiting Ground Zero, where an overwhelming shrine of outpouring and personal notes by strangers and victims' loved ones gave him an idea. A boy's note to his Dad, in particular, showed him that any American could have been a victim of terrorism, and we all needed a place to pay respects each September.

After 10,000 people choked his Belmont Heights neighborhood to visit his memorial of 343 crosses remembering firefighters killed in 9/11, it was moved Sunday morning to the waterfront where bands and fireworks marked the ride's finish.