A video recorded by a passenger travelling on a BART train in the San Francisco Bay Area on Monday showed another fellow passenger yelling racist slurs at and even physically attacking an Asian-descent man.

In the one-and-half-minute video, passenger Charles Wu was harassed by an unidentified white-skinned male, who is seen hurling racial slurs like “Asian n-----" at him. The racist man then proceeded to threaten him with physical violence saying things like “I’ll punch you in the teeth” and “I’ll beat you in your seat.”

As Wu did not respond initially, the racist man went close to him and hit him twice — once on the shoulder and another time across his face. That is when Wu got up from his seat in anger and took a few steps toward his abuser. However, one of his co-passengers managed to calm Wu down soon after. “He’s drunk, man, he’s not even worth it,” the co-passenger is seen telling Wu.

Wu later told the San Francisco Chronicle that no one stepped forward to defend him when the man was yelling racist profanities at him. “No one was saying anything and it was a BART full of people,” he said. “I had enough, so I told him, ‘Sir, you need to stop talking.’”

Wu also added that people spoke up only after the passenger got off the train. “Everyone got loud once he got off, saying he’s a disgrace and stuff like that,” Wu said. “During it, I was just angry and frustrated that this guy is saying all this terrible stuff and no one said anything to stop him.”

Bay Area Rapid Transit Police said they received three calls from riders around 10:10 p.m. local time Monday (1:10 a.m. EST Tuesday), regarding the incident. BART officials believe that the racist passenger got off the train before they reached the scene to investigate the matter. No arrest has been made so far in the case.

“We see a lot of crazy things on BART and I thought it’d be over in no time,” said Wiseley Wu, who filmed part of the attack on his camera and put it on social media. “But it kept getting worse and worse and I never expected to see something like this in front of me, I didn’t know what to respond,” he said.