 INTO THE SHOOTER IS STILL UNDERWAY. 20-YEAR-OLD THOMAS MATTHEW CROOKS FROM BETHEL PARK, PENNSYLVANIA, JUST AN HOUR AWAY FROM THE SHOOTING SITE. LET'S BRING IN CBS NEWS REPORTER NICOLE SKANGA. STILL THE QUESTIONS BEING, YOU KNOW, WHY DID HE DO IT? HOW DID HE GET THERE? HOW DID HE GET SO CLOSE? YOU KNOW, WHAT WAS HIS MOTIVE? WHAT HAPPENED?