A man was caught on cell phone video holding a small knife on a northbound Q train at the Dekalb Avenue station. View Full Caption DNAinfo/Michael Ip

FORT GREENE — Police arrested a knife-wielding straphanger Thursday after he was seen holding the weapon aboard a northbound Q train.

Ysaac Paul, 31, was holding a small knife in his right hand as the train stopped at the Dekalb Avenue station around 1:13 p.m., the NYPD said.

A woman waiting to get on the train recorded cellphone video of Paul holding the knife, according to the New York Post.

[WARNING: The following video contains graphic language.]

The video, taken from outside the train on the platform, shows the man standing by the doors on the opposite side of the train, holding a small knife.

About 30 seconds into the video, he can be seen putting the knife in his trench coat pocket and walking to the other side of the car.

“I have been a New Yorker all my life and I have never seen some s--- like this,” the woman recording the video says.

The video was posted to the Facebook account of Mariah Lopez Ebony. Police would not say if the man in the video was Paul.

Police said passengers on the train feared for their safety.

When officers confronted Paul, he refused to take his hands out of his pockets and resisted arrest by flailing his arms, police said.

Paul was charged with criminal possession of a weapon, menacing, obstructing governmental administration, resisting arrest, disorderly conduct and harassment.

He was previously convicted of trying to obtain transportation without paying in January 2013, according to a criminal complaint.

Paul’s Legal Aid attorney, Rebecca Kavanagh, said her client is innocent until proven guilty. Kavanagh said she requested Paul undergo a psychiatric evaluation in lieu of paying bail, which would be set at $75,000.

"He's not someone with an extensive criminal history and the bail request was very high given the nature of the charges," she said.

Paul is being held pending the results of the examination. He is due in court April 1.