"Go home," he shouts over and over trying to disperse the crowd. "Don't let those f--king n--gers out there fool you!"
"Don't let those f--king trash antifa bulls--t people, fool you!" he continues. "Don't let these pendejos right here -- don't let these f--king a--holes lie to you!"
Pendejo is Spanish slang meaning "idiot."
The protesters were marching for racial equality and the end of police brutality in the wake of George Floyd's death. Floyd, a 46-year-old Black man, died after a white police officer kneeled on his neck for several minutes during Floyd's arrest in Minneapolis, Minnesota on May 25.
One of the protesters accosted in the group on Friday called the incident "very scary."
"We were just trying to cross the street and someone stopped in the middle of the crosswalk and started yelling at the girl in front," Lorena Houghton told The Monitor.
She said the unidentified man ripped a poster out of a woman's hands before reaching for his chainsaw.
"I think that the exact point they were trying to make is that they didn't think that Black Lives Matter was necessary here, but I think he disproved his own point by violently attacking people that were walking on the street."
McAllen Police Chief Victor Rodriguez told the outlet, "We've detained that person and are continuing our investigation into the particular incident."