A British man is being questioned after allegedly threatening to kill 200 people in America, which led to thousands of pupils missing school.
The 24-year-old from South Shields, South Tyneside, was in custody after apparently posting a message on Facebook two days ago.
According to reports, the post was made anonymously on an online memorial page, set up for a Tennessee student who died in October, a local newspaper said. That led schools in Warren County, Tennessee, to tighten security, with limited access to premises.
According to reports around 3,000 pupils were absent from school the next day.
A Northumbria Police spokesman said: "At 2.12pm today police received notification that a man had posted threatening information on Facebook. A 24-year-old man from South Shields has been arrested on suspicion of threats to kill and is currently in custody.
"The message is believed to have been posted on Wednesday. There is nothing to suggest he posed any physical threats to any schools either here or in America. We are currently seeking advice as to who has jurisdiction in this incident."
According to Sky Tyne and Wear, the anonymous message said: "My father has three guns. I'm planning on killing him first and putting him in a dumpster. Then I'm taking the motor and going in fast. I'm gonna kill hopefully at least 200 before I kill myself."
Bobby Cox, director of Warren County Schools, Tennessee, updated parents on Facebook, telling them: "We received notice of violent threats directed at Warren County High School late Wednesday evening. We put an action plan together with the local authorities to ensure the safety of our schools and our campuses across the system."
He added: "Currently the Sheriff's Department is working with the TBI and Homeland Security to trace down the person who posted the message. In the world we live in we can never be too cautious and must take all threats seriously."
The Chattanooga Times Free Press said police were posted to 11 schools in the local area. Kirstin Helm, of the Tennessee Bureau of Investigation, said the agency was unaware of any arrest