Officials don’t know how credible the threat is. FBI is assisting the investigation and they hope find who sent the e-mail. All 17 schools in the area, with 11,400 students, were closed. He added: “It’s definitely a tightrope. We have to keep in mind the safety of everybody involved — students, teachers, other workers in the buildings. It’s a tough decision to make. These seem to be going on throughout the country. They seem to be happening more frequently and they’re very disruptive on many different levels.” Classes will resume Tuesday. Threats of violence targeting schools became a common thing in the U.S. now and probably this will force soon to adopt a standard reaction based on unified protocol of procedure.