Security officials at Sun Coast area schools are on heightened alert after a bomb threat was exposed in Tampa early in the week. School officials here are now encouraging students and employees to be vigilant, both in person and on social media, after a 17-year-old boy was arrested for allegedly planning a Columbine-style mass killing at a Tampa high school. A number of area schools are being re-built with gated single points of entry for security purposes, including Venice and Booker High Schools. Manatee and Sarasota schools open Monday.