By Gabriella Borter and Brad Brooks UVALDE, Texas (Reuters) – The gunman who killed 19 children and two teachers at a South Texas elementary school was able to enter without any confrontation, authorities said on Thursday, contradicting earlier reports that a police officer engaged him outside the building. Salvador Ramos, 18, crashed his pickup truck outside the school at 11:28 a.m. (1628 GMT) on Tuesday, fired several shots at two bystanders across the street and walked into an unlocked door of the school at 11:40 a.m. (1640 GMT), Victor Escalon, a spokesman for the Texas Department of Publi…