Authorities say 18 people have been killed in a head-on collision between two buses in central Nigeria.

Jonas Agwu, a spokesman for Nigeria's Federal Road Safety Corps, said the crash happened early Wednesday morning near Gwagwalada, a town outside of Nigeria's capital, Abuja.

Agwu said investigators suspect the driver of a smaller, older bus fell asleep behind the wheel, causing the vehicle to drift into the other lane and hit a large touring bus. He said at least nine others were injured in the crash.

Nigeria has some of West Africa's worst roads, despite its oil wealth. Massive potholes and poor paving, coupled with aggressive drivers, are blamed for many crashes. World Health Organization data shows Nigeria suffers from one of the world's highest traffic fatality rates.