Marina High school, bomb threat

This is from the OC register:

HUNTINGTON BEACH– County bomb squad officials investigated a threat written on a classroom window at Marina High School today, sending explosive-sniffing dogs in around 8 a.m. following a call from school officials.
Four Huntington Beach police units responded to the initial call after school staff found a threatening message written in permanent marker on a campus window, prompting the evacuation of all students to the school's football field, police Lt. J.B. Hume said.
Classes resumed at about 10:48 a.m. when the campus was cleared of any potential threat, Hume said.
Around 2,700 students milled about the field for the first two periods of the school day, 16-year-old Max Fisher, said.
"I'm not particularly scared, but it's disturbing this threat comes so soon after the one at Westminster High last week," Fisher, a junior at Marina, said. "It's not funny, like all threats to schools, and I wonder when it may become serious."