The man died at the Warrenpoint port in Downtown.
This happened on Thursdays at 2:30 pm and the police remained at the scene.
Northern Ireland (NIAS) said one of the crews responded to 999 calls and that patients were not taken from the scene.
The police said that Northern Ireland was aware of the sudden death in the area of health and safety.
Warrenpoint Executive Director Port Clare Guinness expressed her condolences to the family of a man.
"The PSNI and the Health and Safety Executive were immediately informed of the incident and cooperated with them and all relevant authorities to enable a full investigation to be carried out," she said.
Approximately 70 people are directly employed at the Warrenpoint port.
An additional 200 people work each day in the port.
Harbor Warrenpoint is the second largest port in Northern Ireland.