A Metro-North train derailed just east of the Fairfield station Friday, causing it to hit a westbound train.
The incident occurred at about 6:10 p.m.
Service has been suspended indefinitely between New York Penn Station and Boston.
The MTA said the train that derailed was the 4:41 p.m. out of Grand Central Terminal. The other train was the 5:30 p.m. from New Haven to Grand Central Terminal.
Sixty people have been transported to area hospitals, and five people are seriously injured, one critically according to Connecticut Governor Dannel Malloy.