A British man has been arrested on suspicion of making threats to kill 200 people which led to schools in America beefing up security.
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. 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."
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. We wanted to make sure that we had all the facts before we sent a mass message out via our calling system to you. Currently the Sheriff's Department is working with the TBI (Tennessee Bureau of Investigation) and Homeland Security to trace down the person who posted the message."
Security was being increased at schools and access was to be limited, Mr Cox said. "In the world we live in we can never be too cautious and must take all threats seriously."
Kirstin Helm, of the TBI, said the agency was unaware of any arrest. "Agents with the Tennessee Bureau of Investigation are working with Facebook to try and identify the individual who posted the threat," she said. "So far, we have not identified anyone."
The memorial page was set up for a local student who died in October, a Tennessee newspaper said. Someone wrote on it using a false name. The Chattanooga Times Free Press said police were posted to 11 schools in the local area. Mr Cox told the newspaper: "It's sad that it kept kids home from school when they should be learning and having the best days of their life."