The victims -- ages 28 and 32 -- were both stabbed in the abdomen and buttocks.
Police say the 32-year-old man got into an argument with the suspect on a southbound No. 5 train.
The suspect pulled a knife and stabbed him as well as the 28-year-old victim, who appeared to be a bystander.
One of the victims flagged down a police officer.
The second victim was able to get into Grand Central Terminal and flagged down an MTA police officer.
Both are being treated at a hospital and in stable condition.
A person of interest was initially taken into custody but was later released and police say they are still searching for a suspect.
The motive is unclear as the investigation is ongoing.
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