A 1-year-old boy was fatally injured and his father was seriously injured Thursday evening when they were struck by a vehicle that ran onto the sidewalk along St. Barnabas Road in the Marlow Heights area, a Prince George’s County Fire/EMS Department spokesman said.

The child died later at a hospital. The father probably suffered broken legs, department spokesman Mark Brady said.

Brady said the boy’s mother also was taken to the hospital because she was in shock after the incident, though she was not struck.

The crash occurred about 5 p.m. in the 5100 block of St. Barnabas Road, Brady said.

Brady said witnesses told firefighters that a vehicle moving “at a high rate of speed” on St. Barnabas Road swerved to avoid traffic that had stopped in front of it, and in doing so, went onto the sidewalk and struck the boy and his father.

Cpl. Maria McKinney, a Prince George’s police spokesman, confirmed that account, saying the driver of a blue pickup truck ran off the road and struck the pair. She added that the child was in a stroller.

McKinney said it was “too early to tell” whether speed or alcohol played a role in the crash. She said the driver remained on the scene and was cooperating with authorities .

This report has been udpated.