A boat capsized in Guizhou, and 9 students were rescued. What was the cause of the accident?

On September 18, a passenger ship rolled over in the Cangzhou River in Liuzhi Special Zone, Liupanshui City, Guizhou Province. The passengers on board were mainly students from Cangzhou Town. Mr. Zhao, the first villager to discover the capsizing accident, said that he had a small boat that could carry seven or eight people, so he drove the boat to the site of the accident and rescued nine students.

According to previous information from the Liupanshui Municipal Party Committee Propaganda Department, the passenger ship was a model 8015 passenger ship of Xiling Shipping Company (private enterprise), with a capacity of 40 people. There was an overloading problem at the time of the accident, and the passengers on board were mainly students from Zanggao Town. Due to the wide waters of the Cangzhou River, passenger ships are the main means of transportation for students traveling along the river in Cangzhou Town. It is understood that the passenger ship encountered sudden strong convective weather during its voyage. Analysis by the local meteorological department showed that thunderstorms occurred in Zanggao Town, Liuzhi Special Economic Zone on the evening of September 18, with local wind speeds reaching level 6.