Teen dies, friend in coma after NSW crash

A teenager remains in an induced coma after his friend was killed when they hit a car while riding scooters in Sydney's southwest.

The collision in Rosemeadow on Saturday afternoon killed one boy, 14, at the scene while the other, also aged 14, was airlifted to Westmead Children's Hospital in a critical condition, police say.

The driver of the car, a 25-year-old woman, wasn't injured.

"We've got school resuming next week and one child won't be there with his mates," Mick Timms, Acting Inspector Traffic and Highway Patrol Command, said on Sunday.

"He was a local kid ... everyone needs to be safe on the road, not just at holiday locations."

The incident follows the death of a 21-year-old runner at Penthurst in Sydney's south on Friday night.

Police believe the man was running along the road and slipped as he moved to run into the gutter to avoid a car, but he was hit and later died at hospital.