Ice cream truck driver Joe Esposito told the News-Times of Danbury that the pickup never stopped or slowed down.
The boy was sent in critical condition at Danbury Hospital late Thursday before being brought to Westchester Medical Center in Valhalla, N.Y., where he died.
Police say they're looking for a tan Toyota Tundra made between 2000 and 2004 that has minor front-end damage.