NEW BRUNSWICK - Authorities have upgraded a charge filed against a driver whose car jumped a curb and struck two pedestrians on a sidewalk, killing a 6-year-old boy and injuring the child's mother.

Middlesex County prosecutors announced Wednesday that Shang Zhen Huang now faces a death by auto charge.

The 21-year-old Piscataway man initially faced two counts of aggravated assault stemming from Saturday afternoon's crash on Raritan Avenue in Highland Park.

The child, Chaim Kraus, and his 37-year-old mother were taken to a hospital, where the child died a short time later. His mother remained hospitalized in critical condition on Sunday. Her name has not been released.

Huang was treated at a hospital for minor injuries. He remains jailed on $200,000 bail, and it wasn't known Wednesday if he has retained an attorney.