Four persons were injured Wednesday when a three-car works train and a 57-truck freight locomotive collided in Dammam, the third incident involving the Kingdom's railways in the last two months. The collision occurred near Dammam's Al-Muwasalat housing estate at dawn and left a train driver, two railway officials and one railways security guard injured, while causing what was described as “serious damage” to both trains. Three of the injured were discharged from hospital later in the day. An official from Saudi Railways said the works vehicle was exiting a maintenance shed at the company's main site in Dammam when the collision occurred. The incident, which happened on freight-only lines, did not affect regular passenger train schedules, and the spokesman for the Civil Defense in the Eastern Province said that potential dangers and fuel spillage were quickly dealt with by emergency crews. Wednesday's crash follows incidents in mid-December of last year and late January, the first involving two freight trains that collided at the approach to Haradh Station when a train was guided onto the wrong tracks. A driver and another train official were taken to hospital with minor injuries. In January a train carrying 186 passengers and 14 staff derailed causing minor injuries to the driver and an assistant. Saudi Railways said the crash, which took place 80 kilometers outside of Riyadh as the vehicle traveled to the Eastern Province, could have been caused by excessive speed and promised to investigate the “role of the train driver and his assistant.”