WASHINGTON, June 22 (Reuters) - Up to 55 people were injured and at least one person was killed, perhaps several more, in a collision of two trains in the Washington subway on Monday, the NBC local affiliate TV station said.

The TV station showed the front of one train lying on top of the front of the other train in open-air track in the north of the city. It said emergency workers were trying to free some of those trapped on the trains. (Reporting by David Storey, Editing by Frances Kerry)