BEIJING - At least 21 people were killed -- including 14 schoolchildren -- and 21 injured in two car accidents on Monday, one involving a pileup of more than 100 vehicles.

A modified tricycle carrying 20 children to school plunged into a creek in Songjiang township, Hengnan county of Central China's Hunan province at 7:30 am on Monday. Ten of the children died at the scene and four others died later in hospital.

The other six onboard were injured and are still being treated in hospital, said a county education bureau spokesman.

It was foggy when the accident happened and local authorities are still investigating the cause. The driver, surnamed Chen, has been detained, according to the local government.

The tricycle was actually for agricultural use and was overloaded every day, China Central Television reported.

The report said the children were pupils from nearby Dongtang village and had been taking the tricycle to school every day.

Their parents paid the driver 200 yuan (S$40) every semester.

In a separate accident, seven people were killed and 15 injured when more than 100 vehicles crashed into each other on an expressway in Southwest China's Guizhou province, local authorities said.

The pileup began when a truck crashed into a petrol station in Zunyi county at about 8 am. At least 100 other vehicles then rear-ended each other, according to local firefighters.

Six people died at the scene and one died in hospital. The injured received treatment at the People's Hospital in Zunyi county.

It was also foggy when the pileup happened and traffic backed up for about 20 kilometers after the accident.

Monday's accident in Hunan ignited discussions about the safety of vehicles taking children to school.

The vehicles carry students who live in rural areas or places far from school, but increasing numbers of accidents have happened in recent years.

In one recent case, a 2-year-old child named Han Han died of sunstroke after being locked in a school vehicle by a careless driver for about eight hours in Xi'an, capital of Northwest China's Shaanxi province, according to a report from China Youth Daily in August.

One month earlier, a 3-year-old boy died of sunstroke after being locked in a school vehicle by a careless driver in the southern city of Jiangmen.

The country's General Administration of Quality Supervision, Inspection and Quarantine on July 1 released a regulation about the safety of school vehicles serving primary students.

According to the regulation, every school bus must have the capability for at least 10 students, and schools are forbidden from using double-decker buses or articulated buses.

Every vehicle must have two emergency exits and a "black box" for recording accident data.

A teacher's seat is required on every school bus, and two teacher's seats are needed when there are more than 40 students, according to the regulation.

-China Daily/Asia News Network