A man punched a woman in the face while riding the subway in New York City after she told him to "take a chill pill".
A video of the incident, which went viral on TikTok, shows the heated confrontation in a packed train carriage in the Big Apple.
It comes amid a rise in violent assaults on the city's metro network, with major crimes rising a massive 58.6 per cent during September.
In the clip, the man can be head shouting, "tell me to take a chill pill", as he stares the woman down just inches away from her face.
"Say the word 'chill pill'," he challenges her again.
The woman - who is at least a foot shorter than him - looks at him defiantly in the eye and says "Chill pill".
After she does, the dad delivers a crashing right hand to her face, prompting a chorus of gasps from the appalled passengers.
As he hits her, the woman filming and other subway users can be heard appealing for him to stop.
"You wilin', she a female", the camerawoman says.
A man tells the violent dad to stop but no one intervenes.
It's currently unknown how the altercation started, but a caption on the TikTok video - which was viewed more than 2.5million times before being reshared on Twitter - says he was being hostile when he first boarded the subway.
The post read that he told people to "gtfo out of him & his kid's way".
It also says after the woman told him to relax, and his child repeated the phrase towards him.
"All [the woman] said was he needs a chill pill & his kids repeated it to him and it was just up from there," the original poster captioned the TikTok video capturing the attack.
After the punch, he can be heard saying: "Mind your business — say it again I’m tired if you n***** in my black business, you understand?
"I'm dealing with my f***ing kids, you understand? It ain’t about being a role model, it’s about getting respect from people like you. All these other races out here, mind your business."
He then tells the whole train "when my family on the train, move out the way."
The New York Post reported that the NYPD are currently investigating the incident but that the victim - who hasn't been identified - has not reported the assault.
It comes after NYPD officials announced an "uptick in overall crime" on the city's subway network.
Ninety-six grand larcenies were reported last month, a massive increase on August's 64 and 55 in July.
Meanwhile, standard robberies shot up 18 per cent in September to 52 incidents from August's 44.
