An overloaded school minibus in Gansu Province, northwest China, carrying 64 people crashed head-on with a truck on Wednesday, killing at least 21 children. Four local officials have been suspended for the accident.

Forty-four children were rushed to hospital immediately after the accident. Local authorities say two children are still in critical condition and twelve serious injured.

A kid is being treated at a local hospital in Zhengning County, Qingyang City, northwest China's Gansu Province, Nov. 17, 2011. The death toll in a school bus accident that occurred here on Wednesday morning has risen to 20 following the death of one child later Wednesday. The victims, including 18 preschoolers and two adults, died in a head-on collision between a school bus and a truck in the city of Qingyang.

Official He Genxuan from Health Bureau, Zhengning county, said: "Those preschool children have been sent to different hospitals to receive treatment. We will do all we can to help them to recover."

The school minibus was on its way to a kindergarten on the outskirts of Qingyang city after picking up the children when the accident happened.

The bus had nine seats, but it was jammed with sixty-two children and two adults when it collided with the truck.

An investigation has been carried out by the local government. It shows the bus is run by the kindergarten and the interior fittings were adapted for the bus. As to the cause of the accident, apart from driving on the wrong side of the street at high speed and fog, problems such as overloading and the poor enforcement of safety standards have been highlighted.

Such overcrowding on school buses is common in China and has led to deadly accidents in recent years.