Twelve of the 23 students hit by a car that drove into them in North China's Hebei province remained in hospital on Tuesday, including three with serious injuries.

The incident happened on Monday when a car drove into a group of high school students outside Fengning No 1 Middle School in the Manchu autonomous county of Fengning, the local government said.

The students were walking near or through the school gate during lunch break at the time.

Yang Zengyi, deputy head of the school, told the Beijing Times on Monday that 23 students had initially been sent to the?hospital — 14 boys and nine girls, aged from 16 to 20.

Deputy director of the county's publicity department, Jiao Chunjiang, told China Daily on Tuesday that 12 were still in hospital.

Jiao said a suspect, Yin Tiejun, 48, from the county's Fengshan township, had been detained by police.

Xinhua News Agency reported that three of the students had suffered serious injuries. One had a fractured skull, another a crushed ankle, and the third suffered an eye injury.

The news agency said Yin tried to set the car ablaze by igniting a bottle of diesel but police extinguished the fire and found a gas tank and firecrackers in the trunk.

Yin said during interrogation that these were not for an attack.

He was not driving under the influence of alcohol or drugs.

The Beijing Times reported on Tuesday that Yin's daughter was murdered three years ago. He was upset with the sentence handed down by the court and has petitioned in vain for three years.

Jiao said that the case is still under investigation and it is too early to draw any conclusions on Yin's motive.

Zhao Li, a criminal lawyer in Beijing, said the suspect, if proven guilty, faces at least 10 years in jail.

The heaviest punishment for the crime is the death penalty, Zhao said.

"Although it is reported that the suspect was emotionally stressed before the incident, this cannot be taken as an excuse to inflict injuries on others," he added.

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Cao Yin contributed to this story.