NEW : NTSB investigators are focusing on a fractured rail . NEW : ` ` It is substantial interest to us , '' an NTSB official says . 'New York Times reporter Michael Barbaro reports that the investigation has been delayed because of concerns about safety and cost. " Hospitals say they have treated 70 people .
NEW : NTSB investigators are focusing on a fractured rail . NEW : `` It is substantial interest to us , '' an NTSB official says . One train derailed then hit a train going the other way , officials say . Hospitals say they have treated 70 people .