A small Amtrak locomotive hit a commuter train at Union Station Thursday morning, knocking the train's rear wheels off the track and injuring seven people, officials said.

Cheron Wicker, a spokeswoman for Maryland's MARC service, says the train from Baltimore was hit from behind at about 10 a.m., dislodging two rear wheels. The train remained upright.

Seven people were being treated after complaining of minor head and neck injuries, said D.C. fire department spokesman Alan Etter.

Amtrak spokeswoman Karina Romero said a small locomotive used to move the commuter train to a maintenance facility came in too fast and hit the train while passengers were getting off. Both pieces of MARC equipment are operated by Amtrak, officials said.

No major service delays were expected.

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