Drew Hernandez told Fox News the man was possibly defending a transgender woman being beaten and robbed by Black Lives Matter protesters when the mob turned their attention to him and his female companion. He got into the truck and drove away as he and the woman were being attacked, Hernandez said.
"I think he just felt extremely threatened," Hernandez told Fox News’ Dan Springer. "They chased him... until he finally crashed. When they finally caught up to him, they went nuts.
"This was violent, extremely violent," he said. "Sometimes I forget I'm walking the streets of an American city in the Northwest. Sometimes it feels like you're walking in a Third World county."
A video posted online, which has since gone viral, shows a man sitting dazed on the ground moments before another man runs up from behind and kicks him flush in the face, knocking him out. The victim appeared to be knocked unconscious as bystanders came to his aid.
One witness called police to report up to 10 people "beating the guy," police said Monday. Someone off-camera can be heard accusing the man of trying to run over protesters.
The suspected attacker who kicked the man has not been publically identified by the Portland Police Bureau. The Portland Police Department told Fox News that the investigation is ongoing and the victim is recovering.
Portland police Chief Chuck Lovell said detectives are investigating the attack and requested assistance from the public via Twitter.
"PPB Assault Detectives are actively investigating this alarming incident that resulted in a man being hospitalized," the chief wrote. "If anyone has information about this event please reach out. Public safety is up to all of us."
Information from a Facebook account believed to belong to the suspected attacker indicated he works at Portland International Airport. An airport spokeswoman told Fox News that person has not worked there since 2016.
Violence erupted Sunday as protests got underway in what has become a nightly occurrence. Mobs of protesters have attacked random bystanders and dished out beatings for no reason, Hernandez said.
"It's literally like just one thing after another, he said. "Just these random people, they start physically assaulting."
He said the man seen in the video was near a convenience store away from the protest when the attack occurred. He was taken to a hospital with non-life-threatening injuries and is recovering, police said Monday in a news release.
In the video, a person can be heard off-camera accusing the driver of trying to run over protesters.
The attack comes as Portland continues to grapple with nights of unrest that have increasingly turned violent, leading to shootings, assaults, arson and the hurling of deadly objects at police officers.
Hernandez described the environment in Portland since protests begin weeks ago to developing countries where violence is widespread.
"There's this sense of fear because the people are unpredictable because the crime rates are high and police aren't there to save you," he said. "That's kind of the feeling that I get when I'm walking the streets of Portland."
Fox News' Edmund DeMarche contributed to this report