A phoned-in threat prompted a police response to Somerville High School in Somerville, Massachusetts, on Friday.
City officials said police received the threat around 9:30 a.m. and responded to the school. The building was placed in a "secure and hold" protocol - meaning classes continue but no foot traffic is allowed in hallways or common spaces - while police investigated. It was lifted at 10:45 a.m.
School officials said police searched the building for over an hour but found no signs of any safety issues. Police will remain outside the school for the rest of the day as a precaution.
"We understand the difficult emotions that may come with the announcement of a Secure and Hold, but please know that we take safety and security very seriously and we have these procedures in place for exactly these reasons," district officials wrote in a letter to families.
Students in need of support are urged to reach out to school counselors.
This is a developing story. Check back for updates.