Officials say two passengers got into an argument by the 4/5/6 line at Grand Central, which led to one striking the other in the head with a padlock.
First responders put the victim on a stretcher into an ambulance and rushed the victim to the hospital.
There is no word if police placed anyone under arrest.
This attack is the latest in a series of violent attacks. On Sunday morning, officers arrested a man in a string of deadly attacks on the A train.
* Get Eyewitness News Delivered
* More Manhattan news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube
Submit a News Tip