Then in Murrieta, Calif., police arrested a Riverside County teen who they say threatened to kill one of his teachers on Twitter. Police Sgt. Robert Anderson said in a statement that the 17-year-old Vista Murrieta High School student was arrested at his home after school. Anderson says police acted after a school official confirmed that the threat felt credible.

Two suspects were arrested in connection with an early morning bomb threat at Texas-based Perryton Junior High School. Authorities say that around 7:30 a.m., a call was made to the school, threatening that there was a bomb inside the building. Law enforcement swept the building but did not locate explosives.

Schools, it now appears, are not immune to workplace violence incidents, more often perpetrated in the corporate world by thieves, disgruntled former employees, angry customers and even bitter spouses, and such incidents can destroy a company’s reputation, warns Patrick Fiel, who consults on security issues. He advises that school administrators and their security personnel work with a security expert to help identify possible security vulnerabilities in landscaping, lighting, employee and visitor access and signage.

“Conduct full national background checks on all employees and contractors annually and provide yearly training on workplace violence prevention. Install video surveillance cameras to monitor both inside and outside your business. Video surveillance is a deterrent to potential thieves. It can also be a valuable tool to help identify perpetrators and aid law enforcement before, during and after the incident.”

Fiel adds, “Implement access control and visitor management systems to handle visitor and employee access. All employees and visitors should display proper identification badges at all times. Make sure to immediately update access control systems, ID cards and readers when an employee leaves the company.”