SAN DIEGO (NEWS 8) - The FBI is investigating after local schools are caught up in a nationwide online hoax.

According to the San Diego County Office of Education spokesperson, at least four districts got the same threatening email, Coronado, Solana Beach, Lakeside and Santee. They say they take all threats seriously.

Investigators say it was sent to schools in at least 46 states. It's believed the email originated in Europe.

Coronado police said they were notified of the email threat on Monday, but no schools in the district were placed on lockdown.

Districts are reminding staff of safety protocols, such as ensuring classroom doors and perimeter gates are locked.

Parents and students are reminded to report any suspicious behavior.