A spokesperson for Devon and Cornwall police said:
“A 100m police cordon is currently in place in the Mutley area of Plymouth with a number of properties requiring evacuation.
“Emergency services are working at a property in College Avenue after officers located items which require expert analysis from an Explosive Ordnance Disposal Team.
“The cordon is in place for public safety and to allow suitable access for emergency services at the scene while this work is ongoing.
“Officers carried out a warrant at a property in College Avenue this morning [17 February] where a white British man, aged 26, was arrested on suspicion of possessing a firearm without a certificate.
 “He remains in police custody.
“While carrying out searches and enquiries at the house, officers have located further items which require specialist review. EOD are in attendance carrying out this work.
“At this time there is not believed to be any wider risk and it is not believed to be terrorism related at this time.
“We are unable to say how long the cordon will remain in place for but we will update the public when we have further information.”