Police and an Army bomb squad attended a house in King Alfred Street, Derby, at around 11.30am on Sunday after a number of suspicious items were found during a warrant.
More than 50 houses were evacuated and people were allowed to return to their properties on Monday morning.
On Sunday night, Derbyshire Constabulary said there was no indication it was a terror-related incident.
Superintendent Sarah McAughtrie said on Monday morning: “I would first like to thank all the residents in the area – especially those who had been evacuated.
“This has been a protracted incident, but one that I am happy to say has been brought to a safe conclusion.
“At the house more than a dozen items were located which, due to concerns about their contents, had to be examined and ensured they were safe by colleagues from the explosive ordnance division.
“This is, understandably, a time intensive process and teams worked throughout the night to allow people back to their homes as quickly as possible.
“Just after 8.15am, officers lifted the cordon and residents are now able to return to their homes.
“This type of incident is thankfully rare in our city, however, I would once again reiterate that there is no information at this time to suggest that this is a terrorism incident.
“The 40-year-old man, who has been arrested on suspicion of making or possessing an explosive substance and remains in police custody at this time.
“I would urge anyone who has any information that may be of use to the officers investigating the incident to contact the force.”