Shivanshu Misra (9) and Mahak (5) were crossing the road near FM Radio Centre near Manjit Mudhanpur village when the speeding car hit them, police said.
While the former died on the spot, the latter succumbed to injuries on way to hospital, they said, adding that both the deceased were returning after attending a 'bhandara' in a local temple.
The car driver is still on the run, police added.