Gunmen killed the three young sons of a Palestinian security officer targeted twice before for assassination by Hamas, riddling the car taking them to school with more than 60 bullets — and raising the specter of open war between Fatah and the Islamic group. Intelligence officials accused the ruling Hamas Party of being behind the drive-by shooting, unprecedented in its brutality even for violence-wracked Gaza. The officer had helped crack down on Hamas a decade ago and was twice before targeted by assassins, but was not in the car with his children Monday morning. Full Story