The public are being advised to avoid the centre of Bangor in County Down due to what is understood to be an ongoing firearms incident in which gunshots were fired.
A police cordon is in place on the High Street in the city.
The Police Service of Northern Ireland (PSNI) said it would issue an update in due course.
Videos circulating on social media appear to show armed police on the street confronting an individual along with the apparent sound of gunshots.
Posting on X, Ulster Unionist assembly member Alan Chambers said a “number of shots” had been heard and police are responding while Alliance’s Andrew Muir said police are dealing with an “extremely serious and concerning incident”.
Fellow Alliance assembly member Connie Egan said it was a “truly shocking incident and one which will no doubt be incredibly distressing and difficult for residents to come to terms with”.
“I’d urge anyone in the immediate area around Bangor High Street to please shelter indoors until it’s deemed safe by the authorities.
“I’ve been engaging with PSNI and will continue to do so as things progress.”
