Exclusive video obtained by News 12 shows the tense moments before and after a man pulled a knife and allegedly slashed another passenger aboard a Q train near Atlantic Avenue last week. 

News 12 spoke exclusively with the woman who recorded the incident, who says she hopes everyone involved is held accountable. 

The video begins with a man being placed in a chokehold on the train as shocked passengers react. 

"Stop choking him," one rider can be heard shouting. 

But according to witness Sania Kaila, the confrontation started well before the cellphone video began rolling.

"He sat down and the Black guy immediately, like I heard them arguing, he was like, 'You need to say excuse me,'" Kaila told News 12. "And the bald guy said, 'I did. I asked if you could move your leg.'" 

Sania Kaila said that moments before she started recording, the man pictured in a black sweater was already involved in a separate fight with another passenger. She said the dispute began over a seat and eventually turned physical. 

That's when a 27-year-old man wearing a baseball cap intervened. 

"I'm not saying the Black guy didn't do anything wrong because at the end of the day he didn't have to start a fight over a seat. It was never that deep," Kaila said. "But at the end of the day, you inserted yourself into something that had nothing to do with you." 

After the chokehold was released, the man in the black sweater can be seen charging toward the 27-year-old, demanding to know why he got involved. 

According to police, the confrontation escalated when the man in the black sweater pulled out a pocketknife. During the struggle, the 27-year-old suffered a slash wound to his hand. 

"I followed him because he's leaking a path of blood," Sania Kalia said. "I followed them to see if they're going to tell the police the truth." 

The NYPD says the suspect seen in the video is wanted for assault, and the search for him remains ongoing. 

The injured 27-year-old is expected to be OK.