Schools across the UK were put into lockdown after teachers were sent horrifying threats that children would be deliberately run over by a car and shot.
The terrifying warning was sent to hundreds of British schools, ranging from Devon, in the south west of England, all the way up to the north east.
Police in Cambridgeshire, where threats were also received, claimed that vehicles would plough into as many pupils as possible as they left to go home.
Officers in Durham have now told more than 100 schools that they believe the letters to be a hoax and not 'credible' as a threat and have told them to stand down.
The email, sent at about 10am this morning, read: 'If you try and evacuate them the driver will get out and shoot any student leaving.
Several schools are believed to have been locked down as a precaution, including Marlborough Primary School in Plymouth, Devon (pictured)
'You have a choice here, you can ignore this email and risk the lives of the students you say you care for, or you can listen to what we are telling you.
Several schools have been locked down as a precaution, including Marlborough Primary School in Plymouth, Devon.
The school's headteacher Rachel Summers told the Plymouth Herald: 'We followed procedure by phoning 999, phoning the police, as soon as we received that email.
Chief Inspector Catherine Clarke, from Durham Constabulary, said: 'We can confirm that at this time we believe none of the threats received by schools to date are considered to be credible.
'In the absence of any further threats being received, schools do not need to take any further action.
'If any further threats are received they should be reported immediately to police.
'We are in contact with the schools in our area to give guidance and reassurance.
It comes two weeks after similar letters were sent to schools threatening to detonate bombs left on school property throughout the UK.
Police later announced that they did not believe the threat to be viable, as the letters had been sent from the United States and were demanding money.