MAKUENI, Kenya, July 4 (Xinhua) -- At least nine people were killed and 20 others seriously injured in a bus-truck crash early Wednesday along the busy Nairobi-Mombasa highway in Makueni county in southern Kenya.

Makueni County Commissioner Mohammed Maalim confirmed the 3 a.m.(0000 GMT on Wednesday) incident and said that the injured have been rushed to a local hospital.

Maalim told Xinhua by phone that a head-on collision happened between a commuter bus and a truck. The accident happened near the Sultan Hamud area.

"It was a fiery crash. The vehicles collided head-on and then burst into flames," said Maalim, adding that the bus was heading to Mombasa when the disaster struck.

Kenya's Daily Nation newspaper published photos of the scene, showing the blackened shell of a truck on its side surrounded with wreckage debris.

Eastern Regional Police Boss Moses Ombati told Xinhua that they have launched an investigation into the accident amid fears that the death toll may increase because the injured were seriously wounded.

The Kenyan government has introduced stricter traffic rules to try to curb road accidents, however,the number of fatal incidents have not significantly decreased.

According to an estimation of Kenya's National Transport and Safety Authority (NTSA), an average of 3,000 people die in road accidents annually on the highways.

In April, three major traffic accidents in Kenya claimed more than 32 lives.

At least 15 people were killed and more than ten others injured in two separate road accidents across Kenya on April 22.

According to the police, at least 17 people were killed and 46 others injured on April 10 after a bus plunged into a river in southwest Kenya when the driver tried to avoid an oncoming truck.