A shuttle train derailed this morning at Grand Central Terminal, injuring four of the seven passengers riding on board. New York City transit officials say the train was approaching the station at about 6 a-m. when it hit a bumper block causing it to derail. Four of the passengers sustained minor injuries and were treated at the scene. The train operator was not injured. The shuttle, which runs between Grand Central Terminal and Times Square, resumed service at 6:45 a-m.