One child was killed and another was injured Wednesday in a road accident in the U.S. city of Boston, according to local police.

A minivan crashed into a woman pushing a stroller on a sidewalk, killing a three-year-old boy and injuring a four-year-old girl, Boston Police Commissioner William Evans said.

The girl's injury is being treated at a local hospital and was considered not life threatening. The woman, who appeared to be an nanny, was not hurt in the incident, Evans said.

The minivan had reportedly crashed into another vehicle before hitting the pedestrians.

The incident is under investigation.