What is it about public transportation that lures bigots?

Near Portland, Oregon, a famously liberal and socially progressive city, TriMet commuter train service was temporarily disgraced on Saturday by an unidentified white man who used an antiblack racial slur against a black passenger. Other passengers reportedly remained silent, while the man spewed the hateful words.

The incident was caught on video by three young brothers of color who, after intervening on the victim's behalf, also became the targets of the man's racist tirade.

"You f*cking n*gger!" the man is heard yelling in the direction of an African-American woman, her godmother and a toddler.

"Keep on saying sh*t," one of the young men says, getting the white man's attention.

"What the f*ck are you going to do about it," the white man says, challenging the young men. He then pushes and takes a few swipes at the one who was capturing smartphone video.

The man allegedly began berating the men filming the video. Mic/YouTube

"Film me, n*gger," he says before exiting the train. The man got back on the train briefly, asking the young men to delete the video.

Emilio Herrera, 21, told the Oregonian that it was him and his younger brothers, 18-year-old Romeo and 17-year-old Pablo, who intervened and captured video of the incident, as they rode the MAX light rail train from Beaverton, Oregon, to Portland on Aug. 13.

The fact that nobody else on the train tried to assist the women bothered Emilio Herrera. "Everybody just sat there and watched us," he told the Oregonian.

The man even tries to hit one of the young men filming the incident. Mic/YouTube

TriMet, the public transportation agency, said passengers should feel empowered to help people who are targeted this way. "We are disturbed by the individual's behavior," Mary Fetsch, a spokesperson for TriMet, said in an email to the Oregonian. "In this type of situation it's appropriate for riders to contact the operator and request police to respond or call 9-1-1 directly."

Nitasha Sweaney, 27, came forward as one of the two women targeted by the white man's hate. Sweaney, her godmother and her child were riding in the front car of the MAX train, she told the Oregonian via email.

The man eventually left the train, but came back and asked for the footage to be erased. Mic/YouTube

She said the man had asked her and her godmother for 75 cents. When they said no, he flipped them off and hovered over them. Moments later, the Herrera brothers began recording Sweaney's encounter.

"I have never been in an altercation like this, especially not since having my child," Sweaney wrote in the email. "I've never felt uncomfortable on public transportation but since this I have been extremely alert and uncomfortable."

She added that, sadly, she'll likely get her driver's license to avoid public transportation altogether. "I would never want my child to have to go through that again," she wrote.