Schools in Bracknell were placed in lockdown after an email containing a threat, Thames Valley Police confirmed.
The force said several schools across the region received the email on Thursday morning, most in Berkshire. The threat was assessed immediately and found to be not credible.
There is no information to suggest any genuine risk to pupils, staff or schools, police said.
Bracknell Forest Council said a small number of schools were contacted about a possible threat to welfare, prompting some to activate lockdown procedures. All pupils and staff remain safe and nobody has been harmed.
Brakenhale School was among those affected. Greenshaw Learning Trust said it took precautionary action on police advice and the school returned to normal once the situation was resolved.
A trust spokesperson said students had remained "safe, calm and supervised".
Thames Valley Police said it was liaising with affected schools and carrying out a "thorough investigation" to identify who sent the email. No arrests have been made so far.
Police said they understood such reports could cause concern for parents, guardians, pupils and school staff and would keep schools updated as the investigation progressed.
Katie French, Local Democracy Reporter
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