Schools across Scotland and Northern Ireland were targeted on Monday morning by emails claiming that explosive devices had been placed inside their buildings, prompting evacuations, lockdowns and early closures before police declared the messages a hoax.

Police Scotland confirmed it was investigating threatening messages sent to a number of schools across the country. BBC Scotland reported that the email reached primary and secondary schools in Glasgow, Edinburgh, East Renfrewshire, Perth and Kinross and East Lothian, among other council areas. Some schools in Edinburgh were evacuated, and staff at some schools in Inverclyde were told to work from home for the rest of the day.

In Northern Ireland, the Police Service of Northern Ireland said up to 300 schools had reported receiving the same message, which contained what it called a generalised threat. The force said the email had originated from outside the United Kingdom and that checks had not found anything untoward.

Timing limited the disruption in Scotland

The impact in Scotland was reduced by the school calendar. Many schools are still on their October break, while others held an in-service day on Monday with only teachers in the building. Schools in England and Wales are also on half-term holidays, although similar emails are understood to have reached some schools in other parts of the UK.

James Dalgleish, the City of Edinburgh Council education convener, said he was relieved the threat had been confirmed as a hoax but hugely frustrated that someone would target schools and young people in this way. Because Monday was an in-service day in the capital, he said, the effect on pupils had been more limited, though that did not lessen what he called the stupidity of the sender’s actions.

Glasgow City Council said police were treating the messages as a hoax and that its education director had written to families to reassure them about the steps schools had taken. East Renfrewshire Council said many of its primary and secondary schools received a malicious threat, that staff immediately followed the relevant procedures and that its schools were operating as normal.

North Lanarkshire Council said no schools had been evacuated and all remained open. A spokesperson said activity of this kind disrupts essential services, including schools and nurseries, and diverts staff and resources from the people who rely on them most. The council added that its schools have well-established procedures for such incidents.

Inverclyde Council said schools had responded appropriately throughout the morning based on the information available and expected all of them to open as normal on Tuesday. Midlothian, North Ayrshire, Scottish Borders, East Dunbartonshire and Moray councils also confirmed that schools in their areas had received messages, while Highland and Shetland councils said they were not aware of any impact, with schools closed for the holidays.

The Scottish Government said it was aware that threatening messages had been sent to a number of schools in Scotland and elsewhere in the UK, and that Police Scotland was investigating them as a hoax. Perth and Kinross Council told parents there was currently no information to suggest any cause for concern.

A second wave after East Lothian

Monday’s emails were not the first of their kind this month. Nurseries and primary schools in East Lothian received a similar threat last week during the October break. East Lothian Council said Police Scotland was investigating what was believed to be a hoax communication and that the safety of children, young people and staff remained its highest priority.

Parents rushed to Northern Ireland school gates

The disruption was sharper in Northern Ireland, where term is under way. One school in Lambeg emailed parents asking them to come immediately to collect their children, adding that pupils were safe. At Rosetta Primary School in south Belfast, parents were offered the option of taking their children home.

Education Minister Paul Givan said the email had caused huge alarm and distress among pupils, parents and staff and had led to a number of closures. Speaking at Stormont, he said the message appeared to come from Islamists, threatened that sharia law would be imposed and claimed there were viable devices in school settings. He condemned the level of disruption to young people’s education and said schools should continue to operate as normal.

Assistant Chief Constable Ryan Henderson said the PSNI takes such incidents very seriously but considered the risk to the public low. He said police understood the concern in the community and the disruption caused to students and parents, and were working with the Department of Education and the Education Authority.

Head teachers criticise guidance

Some school leaders said they had been left to make critical safety decisions alone. Claire Robinson, head teacher of Holy Evangelists’ Primary School in west Belfast, told BBC Radio Ulster the advice given to schools had been practically non-existent. Emma Quinn, principal of Rathcoole Primary School in Newtownabbey, said her school went into lockdown and that principals had received conflicting advice.

Rob Kelsall, assistant general secretary of the school leaders’ union NAHT, said bomb threats against schools were utterly unacceptable. He praised staff for acting professionally in extremely difficult circumstances but said some had been left trying to reconcile contradictory advice from multiple agencies. The union has called for a joined-up review of how information reaches schools during such incidents.

The Education Authority said it strongly condemned the emails and that, while some disruption was caused, the majority of schools remained open. Police in both Scotland and Northern Ireland said their enquiries into the source of the messages were continuing.