Watch: The $10K Blackmail-Bomb Threat Behind High School Lockdown

SONOMA COUNTY, CA — A caller demanding $10,000 and claiming bombs were planted at Windsor High School triggered a sweeping law-enforcement response Friday, forcing students and staff into lockdown while deputies, bomb-sniffing dogs, and drones searched the campus.

Sonoma County Sheriff dispatchers received a call at 11:51 a.m. from a man who claimed he was sitting in a black car in the school parking lot, Sgt. Juan Valencia said. The caller demanded $10,000 in cash and warned that several bombs would detonate on campus if the money was not delivered.

A school resource officer on campus alerted administrators, who ordered students to shelter in place.

Sonoma County Sheriff's deputies blocked off the 8000 block of Windsor Road at about 12:15 p.m. and advised the public to stay out of the area as multiple agencies joined the response, including the California Highway Patrol, the Sonoma County Fire District, CAL FIRE, and the Sonoma County Department of Emergency Management, Valencia said.

The threat came during lunchtime, and many students ran off campus as part of the “run, hide, fight” emergency response protocol taught in schools.

Deputies detained a student who ran across campus until they determined that the student fled out of fear and had no connection to the threat, Valencia said.

Authorities locked down the campus and searched buildings, grounds, and nearby streets. They combed the campus on foot, launched drones overhead, and deployed CHP explosive-detection dogs to sweep buildings and vehicles matching the caller’s description. Investigators found nothing suspicious, Valencia said in a statement.

The campus reoponed at about 3 p.m. "We have concluded our search of Windsor High School and have determined that there is no bomb threat to the school," the sheriff's office reported Friday afternoon.

One woman wrote online that everyone on campus was safe: "Don't go to the school the roads are blocked and police are actively searching for someone. No weapons reported."

Investigators now believe the call was a "swatting" attempt — a hoax designed to trigger a large police response, according to Valencia. Authorities said other law-enforcement agencies reported receiving similar calls around the same time.

The sheriff’s office is still investigating the source of the threat.

MORE: Update: Bomb Threat At High School