BEIJING -- Beijing police said Thursday that the traffic accident in a farmers' market that killed four people was caused by the driver's negligence.

A van was driven into a farmers' market in Beijing's northern suburb of Changping around 3 pm Wednesday, killing four people and injuring 12.

Police said the the 45-year-old driver surnamed Xu was not intending harm but did not take due care.

Xu has been detained, and an investigation is underway.

The injured, being treated in hospital, are in stable condition.