Haitian officials say 20 people have been killed when an overloaded bus carrying passengers and merchandise collided with a truck in the country's remote northwest.

The National Ambulance Center of Haiti says 11 people died at the scene of Sunday's accident outside of the northwestern town of Port-de-Paix. Another nine people were declared dead after being transported to hospitals in Gros Morne and Gonaives.

Fatal road accidents are frequent in impoverished Haiti, where police seldom enforce traffic laws and vehicles are routinely overloaded with passengers and goods.

The cause of Sunday's deadly crash is being investigated. It was not immediately clear if the drivers of the two vehicles survived.