The Ministry of Public Security has dispatched a team to investigate a fatal car crash on Sunday morning that killed 18 people and injured one on the 514 provincial highway near Fuyu, northeast China's Jilin province.

At around 5:40 am, a small truck hit the back of a tractor. Then the truck slid into the oncoming lane and crashed into another small truck, according to a preliminary investigation by local police. The cause of the accident is still being investigated, it added.

The Traffic Control Bureau of the Ministry of Public Security said in a statement on Sunday afternoon that it has dispatched a working group led by Liu Zhao, vice-minister of public security, to the scene to investigate.

The ministry has also dispatched 10 supervision teams to various key regions and traffic routes across the country to eliminate safety risks and prevent similar accidents in the future, it added.

Netizens have speculated that the high number of fatalities in the crash might be because the vehicles were overloaded with passengers, which has been a well-documented problem in rural regions.

On April 15, a three-car collision in Fuyu's neighboring Qian'an county claimed 12 lives and injured four. In that incident, a sedan scraped another vehicle on the provincial highway and then crashed into a light truck, causing fire to break out in the sedan and the truck.

The truck was supposed to carry only five people, but it had 15 local onion farmers on board, according to investigation report by the ministry. In the end, 18 local officials were disciplined due to oversights.

China's road traffic safety law prohibits tractors, trucks and cargo vans from carrying passengers. This is due to these vehicles typically lacking the necessary safety measures for passengers, and they can easily tip over during emergencies due to having a high center of mass.