Suspicious

ABC News is reporting, in a story that is not yet appearing anywhere else, that suspicious activity has been detected on rail tracks in the Northeast corridor.

Suspicious activity along the New York-Philadelphia-Washington rail corridor — along with the discovery of a concealed infrared electronic device on the tracks near a rail yard in Philadelphia — has triggered federal and regional investigations, ABCNEWS has learned.

While authorities say they do not want to unnecessarily scare commuters, they say the findings fit the pattern of terrorists casing the rail lines for a possible attack. The devastating train bombings in Madrid, Spain, have forced them to take all suspicious activity seriously, they say.