Two persons, biking without helmets, were killed and a nine-year-old boy was critically injured in two highway accidents near Jamshedpur on Sunday.

While mukhiya Shankar Murmu (40) of Jumal panchayat in Seraikela-Kharsawan died in a mishap on Tata-Chaibasa state highway in Rajnagar, 35km from the steel city, 25-year-old Ghatshila resident Kartik Kisku was crushed to death on NH-33 in Dalbhumgarh, 70km away.

Murmu's son Ayus is battling for life at MGM Medical College and Hospital in Sakchi, and is likely to be referred to Tata Main Hospital in Bistupur.

Rajnagar thana OC Avinash Kumar said Murmu and his family were biking from Jumal to Jamshedpur around 1pm to buy a new mobile phone from a city shop.

At a sharp bend near Hessel village in Rajnagar, a speeding truck hit their bike. While Murmu's wife Visakha, who was also riding pillion, miraculously escaped unhurt, the mukhiya and his son - none wearing a helmet - sustained grievous injuries.

"Passers-by called an ambulance and rushed them to MGM hospital, but doctors declared the man brought dead. The trucker managed to escape with his vehicle. We are trying to track the truck and its driver," OC Kumar said.

An attending doctor at MGM hospital said the nine-year-old boy had sustained head injuries and was undergoing a CT scan. "His condition is very serious. We may refer him to TMH soon," the doctor added.

Earlier, around 6am, Kisku was run over by a dumper at Jairamdih in Dalbhumgarh police station area of Ghatshila subdivision. He was a resident of Shyamsundarpur in the same subdivision and was bound for Jamshedpur.

Ghatshila SDPO Sanjay Kumar Besra said the head-on accident automatically obliterated chances of the youth's survival. "The biker was not wearing a helmet. His skull was crushed on impact. He could not be taken to hospital. We have seized the dumper, which the driver abandoned and fled," the senior officer added.

Police have sent both bodies for post-mortem.