Johanesburg - Four people, including two children, died when two vehicles collided in Warden on Friday, paramedics in the Free State said.Two other people were critically injured, ER24 spokesperson Russel Meiring said."Both patients were found lying next to their vehicle and were in a critical condition. A doctor that had been driving by, had stopped to assist the injured on scene," he said."Treatment as well as advanced life support was provided to both patients before they were transported to Mediclinic Hoogland for urgent medical treatment."The cause of the accident on the R714 was unknown.