BRIDGEPORT - Officials with the National Transportation Safety Board arrived in Bridgeport today to begin an investigation into the Metro-North train derailment and collision that sent 70 people to the hospital yesterday.

Hospital officials say three people remain in critical condition today.

Police say an eastbound Metro-North train derailed just east of the Fairfield station last night, and then clipped a westbound train on another track, which also partially derailed.

Metro-North riders are facing delays and service disruptions in the aftermath of the crash.

The MTA says there will be no Metro-North train service between South Norwalk and New Haven until further notice. Gov. Dannel Malloy said the damage to the tracks is "absolutely staggering," and officials did not give a timetable for repairs.

The federal investigation is expected to take seven to 10 days. Officials say they will be examining the rails and the braking systems in both trains.

State and local officials praised the hard-working emergency responders who quickly worked to rescue passengers. They also noted that the cars involved were relatively new and said that likely played a factor in preventing more serious injuries or fatalities.