A bomb disposal team was called to a city street following reports of unknown chemicals found inside a home.
Houses were evacuated in Eglington Mews, near Angel Road, at 7pm last night.
Paramedics, fire crews and police were called to scene after a man showed signs of being overcome by fumes.
He refused treatment.
Witnesses reported hearing a loud bang from the area earlier in the evening.
People were evacuated from their homes and a 100-metre cordon was put in place while police waited for the bomb disposal team to arrive.
The man at the property was arrested on suspicion of making explosives with intent and taken into custody at Wymondham police station.
The military tested the chemicals and searched the property.
They found nothing of any concern.
Following enquiries by the bomb disposal team, the man was de-arrested and no further action will be taken.
Local policing commander, Superintendent Terry Lordan, said: “We’d like to thank local residents, particularly those who were evacuated from their homes, for their patience and understanding last night.
"The safety of the public and staff involved in responding to these incidents will always be our priority which is why the cordon was put in place as a precaution.
"Following enquiries, nothing of concern was found and the cordon was lifted."
The cordon in Eglington Mews was lifted shortly after 11.30pm.
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