The Garda Síochána Ombudsman Commission has begun an investigation into the circumstances surrounding the death of a man following an incident in Dundalk last night.
Gardaí found a man in a distressed state after they were called to a shop in the Green Acres area of Dundalk at around 9.30pm.
He was detained by gardaí but became unwell at the scene.
The man, who was in his early 30s, was taken by ambulance to Our Lady of Lourdes Hospital in Drogheda. He was pronounced dead just over an hour later.
The Garda Ombudsman's office was alerted and staff went to the scene late last night.
Parts of Avenue Road and Green Acres were sealed off.
State Pathologist Dr Marie Cassidy is due to carry out a post mortem examination today.