The driver, Timothy Weber, 27, of East Hampton, who had been en route to a fire-training session with a colleague, was arrested for driving with a suspended license.
Police say they believe the victim had been drinking.
Weber was behind the wheel of the van belonging to the Springs Fire District just before 7 p.m. Tuesday on Springs Fireplace Road when he struck Luis Gauzhambo, 57, who lived nearby, said East Hampton Police Chief Todd Sarris.
Sarris said Weber swerved to avoid Gauzhambo - who had been walking in the middle of the dark roadway - but it was too late.
"He was in the southbound lane when he was struck. It appears the pedestrian may have been drinking," said Sarris.
A bottle of rum was found nearby.
The victim was rushed to a nearby hospital where he died three hours later.
Authorities are awaiting result of a blood test to determine whether he was intoxicated when he was struck.
Weber was charged with driving with a suspended license.
The van was impounded for safety checks.
