A school of more than 1,000 pupils was evacuated after a hoax bomb threat was made.
St Cuthbert’s Roman Catholic High School was put into lockdown after the bomb call at 08:55 BST and staff dialled 999.
Greater Manchester Police (GMP) said it investigated but found it was a hoax.
The school, which has more than 1,100 pupils, has been closed for the day. GMP said it was investigating.
A GMP spokesman said: “The school implemented a lockdown in response to a suspicious call.
“Officers attended and carried out an assessment which indicated that the call was a likely hoax.
“Officers are investigating the circumstances of the call.”
The trust which runs the school, St Teresa of Calcutta Catholic Academy Trust, said “parents and carers were notified immediately that their children had been removed to a safe distance and there was no threat or danger to anyone present”.