An unidentified person ordered Mark Fitzgerald, 37, at gunpoint out of his SUV, allowing Richard Kamrowski to climb down from the auto unscathed, police said.
Fitzgerald only stopped when other drivers intervened and boxed in the auto on the busy road, authorities said.
The would-be stunt double is 65-year-old Richard Kamrowski, who had gotten into a minor side-swipe accident on Saturday with Mark Fitzgerald, 37.
"I thought he was going to run over me", Kamrowski told the NBC affiliate.
The two men involved in Friday's apparent road rage incident on the Mass. Pike, which was caught on video, were arraigned separately Monday in Waltham District Court. The man with the gun and another driver kept Fitzgerald there until troopers arrived.
Kamrwoski told WBZ the incident started when Fitzgerald swerved into his lane and bumped his auto.
When Fitzgerald drove toward Kamrowski, the latter ended up jumping on top of the Infiniti QX70.
Accumulating snow tonight, risky wind chills to follow
Unsafe cold will follow this winter storm with potential for wind chills to dive below -35° both Wednesday and Thursday mornings. A Winter Weather Advisory and a Winter Storm Warning are in effect across most of the region through Monday at 6:00 p.m.
"I felt that he bumped me, and I kind of, you know, was pushed up", Kamrowski told NBC10 Boston.
"I don't think he stopped", Kamrowski said.
"He kept going fast, slow, fast, slow tried to get me to slide off", Kamrowski said.
Massachusetts State Police arrested both Fitzgerald and Kamrowski, WFXT reported.
NBC Boston was unable to get a statement from Fitzgerald about the incident, as he ran away from their camera and jumped into another auto, slamming the door behind him.
Mark Fitzgerald, 37, of Ashland, pleaded not guilty in Waltham District Court to charges including assault with a risky weapon, negligent operation, and leaving the scene of property damage. In video obtained by WBZ, the unidentified man said he had a license to carry a firearm. Kamrowski, of Framingham, was charged with disorderly conduct. It ended when a man with a gun forced the driver out of his vehicle on the highway.