Police have made an arrest after emails "threatening violence to children and staff" were received by a number of schools in Leeds.
West Yorkshire Police had launched an investigation - with officers "providing reassurance and safety advice to affected schools".
In messages to parents, one primary headteacher said police had been treating the threat as "credible" - and children were being kept indoors for the whole day, with gates locked and windows and doors closed.
In its statement, the force said: "Officers have commenced an investigation into a potential malicious communications offence and have now made an arrest in connection with the matter."
It added: "Contrary to some reports the force has not issued guidance to schools to 'lockdown' and has not stated the threats are credible."
According to Leeds Live, the schools understood to be affected so far are Richmond Hill Academy, Ruth Gorse Academy, Sharp Lane Primary School, Windmill Primary School, Beeston Primary School and Clapgate Primary School.
