Detectives are questioning a British man in connection with alleged threats to shoot dead 200 children at a US school.
Sky Tyne and Wear reported Northumbria Police arrested Reece Elliott, 24, from South Shields, on Friday on suspicion of making threats to kill.
An anonymous post made on Wednesday on a Facebook memorial page set up for a deceased student threatened a mass killing spree, saying: "I'm gonna kill hopefully at least 200 before I kill myself."
Elliott is being held at South Shields police station.
Homeland Security in the US has been informed, and the threats led schools in Warren County, Tennessee, to tighten security.
Some reports said as many as 3,000 students did not attend classes the next day.
The post 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 I'm going in fast.
"I'm gonna kill hopefully at least 200 before I kill myself."
Tennessee Bureau of Investigation spokesperson Kristin Helm said its cyber crime agents are helping in the investigation and the source of the post had not been identified.
It is not yet known whether any potential prosecution will be brought in England or the US, or both.
Warren County Schools tightened security following the threats A spokeswoman for Northumbria Police said: "At 2.12pm on Friday February 8, 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 it posed any physical threat to any school either here or in America."
Bobby Cox, director of Warren County Schools in Tennessee, said: "As most of you are aware we received notice of violent threats directed at Warren County High School late Wednesday evening, February 6.
"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 and Homeland Security to trace down the person who posted this message.
"We have increased the presence of Police and Sheriff's Deputies in our schools today and tomorrow and all schools will limit access into each building to ensure the safety of our staff and students."
The Chattanooga Times Free Press reported police officers were posted to 11 schools in the area.
In December, gunman Adam Lanza killed 27 when he opened fire at Sandy Hook Elementary School in Newtown, Connecticut.
He died at the scene and the body of his mother, Nancy Lanza, was found at his family home. She had been shot in the face.
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