An army bomb disposal unit was sent to a college in Trafford in Manchester on Thursday, Greater Manchester Police said.
It is too early to say whether the alert is linked with investigation into Monday's suicide bombing at Manchester Arena, BBC quoted the police as saying.
According to the police, there was an incident in Linby Street, Hulme.
Several roads are closed and officers are "assessing the situation".
Meanwhile, the threat level "will remain at critical and the public should remain vigilant", British Prime Minister Theresa May has said.