The driver of the pickup was given a citation for driving without a license, while two people were cited for standing in the bed, Corporal Knight said. She said an ambulance was called to the scene, but its services were refused by all but one passenger in the truck who was apparently affected by blowback from the pepper spray.

The motorcyclists’ road trip took place on a windy day after a period of rain, according to Chase Stone, the head of a group of motorcycle riders called East Texas Heat, which took part. The riders often film their trips, some with cameras clipped onto their helmets or hands, and Mr. Stone, 27, usually posts the trips on social media.

The footage of Officer Figueroa was captured by the GoPro camera of Jack Kinney, who said he was holding the device when he saw the officer and truck on the shoulder ahead of him.

“I was, like, I am going to turn the GoPro on him and rotate it for a cool passing view of an officer,” Mr. Kinney, 32, said in a telephone interview Tuesday from Longview, Tex. As he passed, he added, “I kind of saw in my mirror a cloud or something.”

“It wasn’t until we got back to Longview that we viewed it on the big TV and were like, ‘Did he really just spray everybody?’ ”

Mr. Stone said he had been on a motorcycle a distance behind Mr. Kinney, and eventually caught up to the others.