Around 5:45 a.m., witnesses driving southbound on State Road 14 near Newhall Avenue in Santa Clarita, California, filmed an altercation between the motorcyclist and the driver of a silver sedan, according to California Highway Patrol Public Information Officer Joshua Greengard.
In the video, the motorcyclist appears to try to kick the sedan on the right. In response, the sedan veers to the left and briefly collides with the motorcyclist before losing control and crashing into the highway divider wall.
The momentum from the crash sent the sedan toward the middle lane of the highway, where it collided with a white Cadillac pickup truck, causing the truck to overturn.
The driver of the truck suffered "moderate" injuries and was taken to a local hospital for treatment, Greengard said. The driver of the sedan stayed on the scene and was not issued a citation, Greengard said.
After the collision, the motorcyclist continued driving southbound and did not stop Greengard said, adding that police are actively following leads that may reveal his or her identity.
The incident is still under investigation, Greengard said.
The witness who took the video, 47-year-old Santa Clarita Valley resident Chris Traber, said he was on his way to work when he saw the incident.
Traber, who works for a local power company, was riding in the passenger seat when he noticed the motorcyclist pass them in the fast lane, he told ABC News.
About 100 yards ahead, Traber said he saw the silver sedan, which was in the carpool lane, swerve to the right to enter the fast lane, almost hitting the motorcyclist.
"Obviously, it really scared the motorcyclist," Traber said, adding that he could tell by their hand gestures that the two motorists were then engaged in a heated argument.
Traber knew he should start recording when he saw the motorcyclist kick the sedan's passenger side door, he said.
"Hey, something is gonna happen here," Traber said he thought to himself.
By the time Traber began recording, the motorcyclist had driven to the other side of the sedan and kicked the door on the driver's side, Traber said.