Authorities say the female suspect threw bleach at the victim at the 14th Street subway station on Seventh Avenue and then fled the scene.
Police say the victim was standing near the token booth when the suspect attacked her and that it appeared to be unprovoked.
A man who witnessed the incident said he tried to help the victim.
"The lady was messed up, she had pink all over her," the witness said. "She was messed up but she didn't say nothing, she kept her mouth shut because I guess she was in shock."
The witness said the suspect got some bleach on his pants as well. Bleach stains were also visible on the ground.
Officials describe the suspect as a black female in her 30s.
The victim was sent to Lenox Hill HealthPlex in stable condition.
The search for the suspect is ongoing, and anyone with information is urged to call police.
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