According to Sussex Police, they were called to Howard Road in Sompting, which is near the A27, at around 4.45pm on Tuesday, May 21, to reports of a man having a medical episode.
The ambulance service also sent vehicles and paramedics to the scene.
There were reportedly at least two police cars and at least three ambulance service vehicles at the scene.
On Wednesday morning, a spokesman for the ambulance service said they had been called to reports a man had collapsed in the road. They said: "Ambulance crews attended the scene and attempts were made to resuscitate the man.
"Sadly despite the best efforts of everyone at the scene, these attempts proved unsuccessful and the man died at the scene. Our thoughts are with his family and friends."