B737 Undifferentiated or Other Model
Distraction; Workload; Situational Awareness; Confusion
ATC Issue All Types; Ground Incursion Runway
Flight Crew Rejected Takeoff
Human Factors; Procedure
Tower cleared us for takeoff and then cleared another aircraft to cross the same runway.  We discontinued takeoff roll at near taxi speed.  Other aircraft had just started to cross the runway at other end after landing on the parallel.  Since the runway is 11000 feet long the aircraft were separated by over 1 mile.ATC cleared one aircraft to takeoff and another aircraft to cross down field at the same time.
After clearing us for takeoff tower cleared an air carrier to cross our runway.  The air carrier apparently didn't hear our takeoff clearance because he crossed the hold short line.  We had just advanced the power for takeoff.  Immediately upon hearing the crossing clearance I told the Captain not [to] takeoff and made a quick radio call to the tower that we were not going to takeoff.  We had just started to move and the captain quickly reduced power and brought the aircraft to a stop.  It was uneventful for us.Tower controller error.
B737 pilots report of being cleared for takeoff then Tower clearing another aircraft to cross downfield.  Pilots abort takeoff.