Parameswaran of Kemmanaickkenpalayam, near Sathyamangalam, with his 39-year old wife and sons, aged six and four, were proceeding to Puliampatty in a two-wheeler when the mishap occurred near Vinnapalli, they said.
The six-year old boy died on the spot while Parameswaran succumbed to injuries in a hospital, where his wife and the other son are being treated.
After hitting the two-wheeler, the van also dashed against a pedestrian woman, killing her on the spot, police said.