Authorities in northwest China said Monday they had formally arrested the head of a kindergarten operating an overloaded bus that crashed into a truck, killing 19 children and two adults.
The nine-seater mini-bus was carrying 64 people when the accident happened in Gansu province's Zhengning county on Wednesday. The bus driver, who died, was reportedly driving on the wrong side of the road above the speed limit.
"Li Jungang, the chairman of the kindergarten, was arrested on charges of causing a traffic accident," Yuan Suiming, deputy chief prosecutor in Zhengning, told AFP.
"He could be given a sentence of more than seven years in prison."
Li violated traffic laws and regulations by re-fitting the bus and having the seats removed to allow more passengers to be crammed in, the official Xinhua news agency reported.
The kindergarten -- which has more than 700 children enrolled -- only had four mini-buses at its disposal, and seats in all four vehicles had been removed, the report said.
Local authorities have said families of the victims will each receive 436,000 yuan (ê69,000) in compensation for their loss, it added.
Earlier reports said police had also detained the driver of the truck and two local officials, and that the heads of the local education bureau and traffic department were under investigation.
Children are often crammed into buses for their journeys to school in China, especially in rural areas, despite strict regulations limiting passenger numbers.
Parents of students at the kindergarten in Zhengning said school buses had been overloaded for years despite several complaints, according to previous reports.
China's education ministry responded to the accident last week by ordering education authorities and schools and kindergartens across the country to carry out safety checks on buses.