A viable device has been discovered during a security alert at Main Steet in Glenavy.
The item has since been removed for forensic examination.
A number of people who were evacuated have been allowed to return home.
Ammunition technical officers attended the scene this morning.
Detectives investigating would appeal to anyone who may have any information about the incident to contact police on 101 quoting reference number 292 of 16/06/21.
Alternatively, a report can be made using the online reporting form via www.psni.police.uk/makeareport. Information can also be provided to Crimestoppers anonymously on 0800 555 111 or online at www.crimestoppers-uk.org.