A security alert that forced the evacuation of two schools was a hoax, police have confirmed.
Hundreds of students at The Hewett Academy, off Hall Road, Norwich, and Sir Isaac Newton Sixth Form College, in Bethel Street, were told to leave.
Norfolk Constabulary said there was "no credible information that the threat was anything other than a hoax".
Police have now left both Inspiration Trust-run sites, which are about two miles apart.
The force added inquiries were under way to find those responsible.
"Officers would like to speak to anyone with any information relating to the threat or believes they may know who was involved," said the force.
Pupils at the academy and the college had been removed as a "precaution" around lunchtime, police said.
In a statement, a trust spokesman had said: "We received a suspected bomb threat earlier today and immediately notified police.
"The safety of our students is our utmost priority and we decided to evacuate the buildings as a precautionary measure.
"We are working closely with the police to resolve the matter."