as investigators worked to piece together a motive. ramos s aunt shelby telling me she s in disbelief. my heart hurts for everyone right now. do you have any idea why he flipped. people go through things and nobody understands. everybody has, i don t know what was going on. reporter: while he had no known criminal history or record of mental health illness, a series of private messages posted on facebook give a chilling warning. the third post, less than 15 minutes before arriving at the school was i m going to shoot an elementary school. across texas, emotions running high. former congressman beto o rourke running for governor in texas disrupting his opponent greg abbott s news conference on wednesday saying another shooting would happen without real reform. you re doing nothing. no. he needs to get his sir, you re out of line. reporter: as so many others struggle to make sense of yet another mass shooting. this morning the painful images are continuing t
a firm timeline of the events. the department of public safety director answering a question wednesday about how long the suspect, 18-year-old salvador ramos was the promises before law enforcement killed him. i can t it is within 40 minutes, an hour. i don t want you to give you a particular time line. but bottom line is that law enforcement was there and they did engage immediately. reporter: and as more video emerges. a law enforcement source telling nbc news this brief clip shows the gunman running into the school dressed all in black, long gunnin hand. inside he was confronted by an armed school resource officer and kept going and made his way inside. that is when ramos locked himself in a classroom and began his rampage. border patrol officers eventually opened the door and exchanged gunfire with ramos, killing him.