US investigators are examining a broken section of rail to see if it is connected to the commuter train derailment and collision outside New York City that left dozens injured.
Meanwhile, the focus begins to shift towards clean-up and rebuilding ahead of challenging times for travellers and commuters along the Northeast Corridor.
A member of the National Transportation and Safety Board said a fractured section of rail is of substantial interest to investigators and a portion of the track will be sent to a lab for analysis. Officials also said the incident was not the result of foul play.
The crash between the two Metro-North trains damaged the tracks, snarling travel in the Northeast. The crash caused Amtrak to suspend services between New York and Boston.
Connecticut's governor said commuters should make plans for alternative travel through the area.