NEW : NTSB officials should be on site by 9 a.m. Saturday , spokesman says . One train derailed then hit a train going the other way , spokesman says . Two hospitals have treated the injured people , officials say ; 2 are critical . A mayor says it will take weeks to get train traffic moving again on that key corridor .
NEW : NTSB officials should be on site by 9 a.m. Saturday , spokesman says . One train derailed then hit a train going the other way , spokeswoman says . Two hospitals have treated 67 injured people , spokespeople say ; 2 are critical . A mayor says it may take weeks to get train service moving again on that key corridor .