A Cupertino high school has been declared safe by Santa Clara County sheriff's deputies Thursday after a search following a bomb threat against a teacher came up empty, a sheriff's lieutenant said.

Santa Clara County Sheriff’s Department Lt. Rick Sung said the all-clear was given at about 11:10 a.m. after bomb-detecting dogs found no explosive package or device.

McClellan Road and a number of surrounding roads were closed during the investigation but have since been reopened.

Santa Clara County authorities received a report from San Jose police at 6:39 a.m. of the threat, Sung said.

Police reported a vandalism incident at Lynbrook High School, located at 1280 Johnson Ave. in San Jose, where graffiti there referenced the bomb threat at Monta Vista High, Sung said.

A specific male teacher, whose name hasn't been released, was referenced in the threat, he said.

Because of its close proximity to Monta Vista High, Lincoln Elementary School, at 21710 McClellan Road, was also closed, Sung said.

Monta Vista High and Lincoln Elementary will remain closed for the rest of the day, but will resume classes on Friday, Sung said.

All other Cupertino schools are conducting business as usual after scans of the campuses revealed no suspicious packages or devices, he said.

No threat was made toward Lynbrook High School.

The sheriff's office is continuing to investigate the incident, Sung said.