The rear passenger car of an Amtrak (search) train derailed slightly in this city, leaving two passengers with minor injuries and disrupting some Metro-North commuter service, officials said.

The Acela Express (search) train, traveling from Boston to Washington, D.C., was carrying 60 passengers and 12 employees when it got stuck on the tracks while backing up slowly about a mile south of Union Station (search) Thursday night, Amtrak officials said.

The rear passenger car came partially off the tracks, said Vernae Graham, a spokeswoman for the rail service. Graham said it was not immediately clear why the train was backing up.

An overhead wire was torn down, and utility officials turned off power to the tracks.

A Metro-North train took stranded passengers back to Union Station, where they were to take buses to their destination.

One passenger was being treated for minor injuries at Yale New Haven Hospital, and another was treated and released, said Metro-North spokeswoman Marjorie Anders.

Anders said Metro-North service from the New Haven, Milford and Stratford stations would be disrupted Friday as the tracks and wires were repaired. Morning commuters at those stations would take express buses to Bridgeport, where Metro-North service would resume, she said.