A college has been forced into lockdown after an police were alerted of an incident involving an "intruder on campus".
The incident took place this afternoon at Bilborough College and the nearby Nottingham University Samworth Academy.
One concerned parent said his son hid under a table at Bilborough College for around half-an-hour.
The parent told the BBC that his son and his Year 13 classmates "hid under tables for about 30 minutes" as police attended the college.
Bilborough College in Nottingham
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Nottingham University Samworth Academy
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The email continued: ""Our college is a safe and secure environment and so the lockdown is a highly effective response to such an incident.
"We are now continuing with the college day while remaining vigilant as always in terms of safety and security."
A spokesman for Nottinghamshire Police said an unauthorised person was reported on the grounds.
"No knife seen or reported," the force added, saying the incident was now closed.