How did doctor tenmas son tobio die in the 2003 astro boy series.all it shows is tobio getting on his flying bike thing and then going into this tunnel in the minestrey of science?

In the Uncut (Japanese) version, it shows that after Tobio rides off on his bike, he gets hit by a truck and killed. This scene was removed in the English version (and possibly other versions as well) due to being thought to be to violent for kids, despite the fact that his death is what kicks off the entire series.