Schools across the UK have been put on lockdown after threatening emails were sent on Wednesday suggesting they would be “targeted in an attack later today”.

Durham Police said it had received a number of calls from schools who had received the email, and that forces “across the country are also believed to have reported similar incidents”.

The correspondence reportedly warned that “pupils would be run down if they left the building”.

Schools in London, Durham and Cambridge have been affected, but forces across the UK are said to be responding to the threats.

The Met confirmed it was dealing with a “number of reports relating to malicious communications” and said they were currently being treated as hoaxes.

“There is no evidence to suggest that this is terror-related,” a spokesperson said. 

West Midlands Police issued a similar statement, confirming it was investigating emails sent to a number of schools from 9.45am, but added that they were believed to “false and malicious”.

“There is nothing to suggest there is any credible threat to any of the schools,” a spokesperson said. “We take hoaxes extremely seriously. They cause disruption and alarm to the public as well as diverting police resources”

According to the Cambridge Times, the email said that at 3.15pm a car would drive into as many students as possible as they tried to leave.

Durham Police said it was taking the incident extremely seriously, and said forces are working together to investigate the threat, and who might be behind it.

“We are requesting that parents do not ring the police as we are in contact with the schools to offer advice and reassurance, and to keep them updated on the investigation,” Durham police said in a statement.

The Plymouth Herald reported that schools across the area had been put on lockdown and that some were “refusing to let children leave, despite parents having been called to collect them”.

The Plymouth Herald report quoted Sergeant Rachel Ward of Plymouth South neighbourhood as saying the force was in the process of contacting as many schools and colleges as possible alerting them to the email and the likelihood it is a hoax.

A spokesperson for Devon and Cornwall Police said it was aware of a series of malicious communications to schools in the area. 

Less than two weeks ago, on March 19, more than 400 schools and colleges around England received hoax bombs threats which led to hundreds of schoolchildren being forced to evacuate school buildings. 

Fake bomb threats were sent to schools in Northumbria, London, Yorkshire, Lincolnshire, Avon and Somerset.

Police said at the time that they believed the emails originated from the US.