A 6-year-old boy riding a dirt bike Friday was hospitalized after colliding with a truck hauling a horse trailer in Mansfield, Burlington County, police said Saturday. The boy was struck by the trailer’s rear fender after the truck swerved to avoid him when he entered the roadway, a township police report said. The boy was treated for injuries on the scene, then taken to a hospital in Trenton. He was thrown from the bike during the crash, police said. Township police Sgt. Dan Pachuta would not comment on the boy’s condition, but said he was still alive. The crash was reported at 6:30 p.m. Frid…