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. It happened near the Sultan Hamud area.

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

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

The Kenyan government has introduced stricter traffic rules to curb road accidents, however, fatal incidents have not decreased enough.

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.?