Increased security at 2 South San Francisco high schools

SOUTH SAN FRANCISCO, Calif. (KGO) -- There's beefed up security at two South San Francisco high schools in the wake of a threatening letter targeting students and staff.

The letter mentioned South San Francisco and El Camino High Schools. Police have not confirmed if the threats are valid. Both schools are allowing students to stay home if they feel unsafe. They'll grant an excused absence, as long as parents notify their child's school first.