SEATTLE (AP) — Federal authorities in Seattle have charged two people with a terrorist attack on train tracks, suggesting they were motivated by opposition to the construction of a natural gas pipeline across British Columbia when they interfered with the operation of a railroad in Washington state. Samantha Frances Brooks and Ellen Brennan Reiche, both of Bellingham, are accused of placing “shunts” on Burlington Northern Santa Fe tracks Saturday night. Such devices consist of a wire strung across the tracks, mimicking the electrical signal of a train. The devices can cause trains to automatically brake and disable railroad crossing guards. The two were released from custody Monday pending a Dec. 14 court appearance. Their attorneys declined to comment.