Police: Man slashed inside Borough Hall Station in Brooklyn; suspect on the loose

The NYPD says a man was slashed inside the Borough Hall Station in Brooklyn Thursday morning and is currently in the hospital.
Police say this all started with an argument on a southbound 4 train platform at Borough Hall between two men in their 20s. According to authorities, one of the men pulled out some kind of an object and slashed the other man in the arm.
Moments after the slashing, the victim is seen on video sitting on the train platform. Police surveyed the area with flashlights along with train crews searching for the object used. Police say the fight took place on the platform, but according to a witness, there might have been a train waiting at the station.
The slasher is still on the loose.