At least six people were killed in a petrol tanker explosion and dozens injured early Sunday along a key highway in northwest Kenya, police said.Five of the victims died on the spot while the sixth died in hospital in Kamara area along the Eldoret Nakuru highway, Xinhua quoted Francis Kirathe, Nakuru County Police commandant, as saying. "The deceased were burnt beyond recognition after the tanker rolled down and exploded," the official said, adding several people were still missing. He said security officers were searching for the missing people and launched investigations into the cause of the incident which also left six other people in critical conditions.