Armed police were called to Dale Street in Ulverston at 7.43pm yesterday following reports of a man in significant distress.
Emergency services remain at the scene and a wider evacuation has been carried out for public safety after concerns were raised.
Emergency services have identified the presence of a potential firearm within the address and a substance, believed to be noxious, is also being intermittently released from inside the address, police said.
Chief Superintendent David Pattinson said: “We appreciate that the current emergency services activity in Ulverston may cause concern for the local community.
“Assessments are ongoing and will take some time to safely carry out.
“Armed response officers remain at the scene, and a cordon remains in place to ensure the safety of those in the area.
“Those evacuated are all cared for and being accommodated with families and friends or in nearby facilities.
“We continue to thank you for your on-going support.”
The incident has resulted in road closures and the evacuation of nearby residents.
Members of the public are advised to avoid the area.
Anyone with concerns is encouraged to approach officers at the scene or contact Cumbria Police on 101.
Courtesy of The Westmorland Gazette | North Lancs