It happened after 11:00 p.m. in the 6800 block of Ridge Avenue near Parker Avenue.
Police said an 8-year-old and 13-year-old girls were struck by a passing car.
Both were rushed to Einstein Medical Center but were transferred to St. Christopher's Hospital for Children. They are both listed in critical but stable condition.
The driver of the striking vehicle stopped nearby.
Police said the motorist was cooperating. No charges had been filed as of early Friday morning.
The accident remains under investigation.