Officers remain at the scene in King Alfred Street, Derby, where a number of houses have been evacuated.
There is currently no indication as to when residents will be back in their homes, however, officers and partners are working as quickly as they can to bring the incident to a close.
Chief Superintendent Tracy Lewis, said: “I would first like to thank everyone for their support and understanding during today’s incident. At the forefront of our minds is the safety of all those in the area, as well as staff working at the incident, and I know they are working hard to allow people back as quickly as it is safe to do so.
“I am also aware that people in the area will be concerned and I would like to reassure them that there is no indication at this time that this is a terror related incident.
“A man has been arrested on suspicion of making or possessing an explosive substance. He remains in police custody and officers from the force are continuing their enquiries.
“I would urge anyone who has any information that may be of interest to the investigation team to contact the force with reference 282-051221.”