A car accident in Ethiopia's central Oromia regional state has killed 11 people, an official said on Friday. Aschalew Alemu, Public Relations Chief at East Shoa Zone Police Department of Oromia regional state, said the accident happened when a bus carrying 40 passengers collided with a heavy-duty truck on Thursday evening. He added that 31 other people who suffered light and heavy injuries have been taken to nearby health stations for treatment. Police has not yet determined the cause of the accident. Alemu warned the public to avoid night time travel and overcrowded buses to lessen traffic accidents. Despite having one of the lowest per capita car ownerships in the world, deadly traffic accidents in Ethiopia are common with blames put on bad roads, flawed driving license issuance system and lax enforcement of road safety. Traffic accidents during the Ethiopian Fiscal Year 2016/17 that ended on July 8 have led to the deaths of 4,500 people, according to Ethiopia Federal Transport Authority (FTA). The authority is toughening driving license regulations and is digitizing Ethiopia's transport regulation system at a cost of 95 million U.S. dollars in a bid to reduce the high accident rate on Ethiopia's roads. With a growing economy and a rising middle class, the East African nation has for the past several years recorded an average of 11 percent growth in vehicle numbers.