KUNMING - One student died in a hospital on Sunday, bringing the death toll to seven, after an overloaded minivan with mostly students aboard plunged into a valley in Southwest China's Yunnan province on Saturday, local authorities said.

An eight-seat minivan carrying 12 students and one elderly man tumbled into a valley nearly 78 meters deep in Guangnan county in the Wenshan Zhuang and Miao autonomous prefecture at about 9 am, the county publicity department said in a statement.

Gong Mingyong, who was injured in the minivan, with his father at Wenshan hospital in Yunnan province on Saturday. [Liu Juqing / for China Daily]

Six people, including the driver, four students and the elderly man, died instantly.

Eight other students were injured, said the statement. The students, aged 14 to 15, were all in junior high school.

Among the other seven hospitalized students, two are still in serious condition, it said.

A police investigation found that improper driving on the mountain upslope had caused the accident.

Police at the crash scene of a minivan carrying 12 students that plunged into a nearly 78-meter-deep valley in the county of Guangnan, the Wenshan Zhuang and Miao autonomous prefecture, Yunnan province, on Saturday. Liu Juqing / for China Daily?

It was the second traffic accident involving student fatalities in Yunnan within a week and one of many recent such incidents across the country. These accidents have aroused national concern over school transport safety, especially in rural areas.

On Wednesday, two rural primary school students died and another 20 were injured after a horse-drawn cart they were riding collided with a truck in Yunnan's Qiubei county.

The driver has been ordered to pay the family of each deceased student 300,000 yuan ($47,400).

The government immediately banned farm vehicles, unlicensed buses and vans from transporting students in the county.

Schools are few and far between in the Chinese hinterlands. Buses, meanwhile, are relatively new: in the past, most children walked to school.

The issue was thrown into the spotlight after a nine-seat school bus illegally carrying 64 people collided head-on with a coal truck in northwest Gansu province on Nov 16, killing 19 pre-schoolers and two adults and injuring 43 others.