People pass by a victim and damaged vehicles after a truck ran into a crowd in southern Guangdong Province on Wednesday, November 5, 2008. [Photo: xkb.com.cn]

At least four people, mostly high school students, were killed and 20 others were injured after a man intentionally drove a truck into a crowd in southern Guangdong Province on Wednesday, officials said.

The male driver was shot dead and three of the injured were in critical condition, said Cai Xinhua, government spokesman for Zhuhai City, where the incident happened.

Local residents said the driver, who was from central Hubei Province, had a dispute over traffic violations with local police some days ago and had vowed revenge. Their accounts have not been confirmed by officials.

"The three seriously injured were in a coma," Cai told Xinhua, and were expected to undergo surgery.

Witnesses said the truck plowed at high speed into crowds of students who were leaving the Chendong High School at Baijiao Township at about 5 p.m. on Wednesday as classes ended.

Yang Chunmei, a 7th-year student, sustained minor limb injuries in the incident as she rode away on her bicycle.

She told Xinhua she saw a "crazy" truck rushing into the school from the back door, running through the school yard and heading to the front door.

"It all happened so fast. I even saw a person hanging on the moving truck," said Yang, who is being treated at the Zunyi Hospital of Baijiao Township.