Four arrests have been made after a main road through Rhyl in Denbighshire was cordoned off by armed police.
North Wales Police denied rumours on social media of a shooting in Wellington Road on Monday evening.
Ch Insp Martin Best said there had been an "incident" but gave no details.
"We would like to reassure the local community that officers remain in and around the area of Wellington Road which remains under police cordon," he added.
The four people arrested remain in police custody.