KUNMING - One student died in 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 60-meter deep valley in the county of Guangnan, Wenshan Zhuang and Miao autonomous prefecture, at about 9 am, the county publicity department said in a statement.

Six people, including the driver, four students, and the elderly man, were instantly killed, and eight other students were injured, said the statement.

One of the eight students died in hospital Sunday. Among the other seven hospitalized students, two remained in serious conditions, it said.

A police investigation said the driver's improper operations on the mountain upslope have caused the mishap.