A 15-year-old girl's foot was crushed yesterday when she apparently tried to hop on a slow-moving freight train in Northeast Philadelphia, officials said.

The girl, not immediately identified, was in serious condition at St. Christopher's Hospital for Children, said Officer Beth DiDonato, a police spokeswoman.

The 1:55 p.m. accident on the Northeast Corridor line near Orthodox Street and Trenton Avenue in Frankford disrupted service on SEPTA's R-7 rail line to Trenton and on Amtrak between Philadelphia and New York for up to an hour.

Sandy Compo, a spokeswoman for Conrail, the regional freight line jointly operated by CSX and Norfolk Southern, said witnesses reported that the girl tried to "hop or climb on a fright train."

Initial police radio reports indicated that the train operator apparently did not know what happened and continued for a distance before being notified.