The victim, identified as Muskan, lives with her family in the Transit Camp at Govindpuri. Her father died a few years back and her mother works as a domestic help, police said.
The South Delhi Municipal Corporation truck allegedly hit the girl as she was crossing the road with her mother this afternoon. The condition of Muskan is stated to be critical.
Although the driver of the truck fled the spot following the accident, police arrested him later. The accused has been identified as Premnath (42), a resident of Najafgarh, police said.