A number of houses have been evacuated in the Woodville Avenue area of Lurgan as part of an ongoing security operation.
Police have conducted a number of searches at properties in the town this morning and four men have been arrested.
Two are 22 years old, one is 24 and the fourth is 46.
Three were arrested in Lurgan and the 46 year old in Coalisland.
They are being questioned at a Belfast police station.
Four men have been arrested in Lurgan by police investigating dissident republican activity. A number of searches have been carried out. pic.twitter.com/5mVlaPhqLV
— BBC Newsline (@bbcnewsline) September 21, 2016