At least 13 people were killed in a road crash involving multiple vehicles on the highway to the Kenyan coastal city of Mombasa, police said Saturday.Most of those killed were pilgrims on the way to a prayer site.The incident in the Salama area happened after midnight when a truck driver tried and failed to overtake another truck, swerving and causing a collision with vehicles, including a van carrying pilgrims, according to local police.The driver and at least 12 passengers in that van died at the scene, police said.The pilgrims were going to a prayer site in Nakuru County, west of the Kenyan capital of Nairobi, said Martin Kivuva, Archbishop of the Catholic Archdiocese of Mombasa.It was not clear how many pilgrims were in the van, or if there were any survivors.Road accidents are a problem across Africa. The accidents often are blamed on poorly maintained vehicles, excess speed and poor road conditions.