The crash happened in Downpatrick Street just before 10am on Wednesday.
Police said the man was a pedestrian.
Local MP Margaret Ritchie offered her condolences to his family.
"I was deeply saddened to learn of the sudden and untimely death of this Crossgar man," the SDLP politician said.
"He was a former health service worker and has been a stalwart of the community in Crossgar, although advanced in years. His passing in such tragic circumstances will numb the entire community, many of whom would have known him well.
"I offer my heartfelt condolences and sincere sympathy to his family and wider family circle at this very difficult time."
The road remains closed at this stage, police said.
Anyone who witnessed the incident has been asked to come forward.