Sachin was holding his seven-year-old sister’s hands while crossing the NH-8 expressway.

That was the last time witnesses near Rose Land High School — including their school van driver — saw of the two. In a flash, a truck zoomed out of the fog and ran over the siblings.

Komal died on the spot; Sachin is admitted at Paras Hospital in Sector-43.

The driver sped past after the incident — witnesses have told police that the truck had a Rajasthan registration number, though no one could take it down.

Sadar police have registered a case of rash and negligent driving against the absconding truck driver based on the complaint lodged by the children’s father, Naresh Yadav.

“There was fog in the morning and it is possible that the truck driver did not see the children crossing the road,” Sadar SHO Maha Singh said.

The van driver has told the police that he carried 15 children from Sector 10 to Roseland School. He claimed he was helping the children cross the road when “they got disorganised, and the accident took place”. But Investigating Officer, Sub-Inspector Hans Raj Singh, said the van should not have dropped the children on the other side. The driver, he said, should have gone further ahead, till Rajiv Chowk, taken a U-turn and hit the lane where the school is located.