The victim, 54, was attacked in Union Square station on Wednesday at 10:10pm
Woman was slashed across her left shoulder, collarbone, and upper chest
Another victim was attacked on the L line platform in the station on Tuesday
The man was slashed in the neck with a pocket knife and blood was seen on floor
Both victims were taken to Bellevue hospital and are in a stable condition
It comes after a series of attacks on the New York City subway system