Nine people were injured yesterday when a Bulgarian freight train and a Greek passenger train collided near the town of Serres in northern Greece, in an accident that experts said was probably caused by driver error. The two trains collided just outside Rodopolis station, on the Thessaloniki-Alexandroupolis line, at 7.45 a.m. as the passenger train, with 28 people aboard, was pulling out and the freight train was arriving at the station. Although both trains were traveling at low speeds when the accident occurred, the passenger train’s engine burst into flames after the impact. Some 30 firefighters were called to the scene to help put out the fire. Five railwaymen were injured in the crash – the Bulgarian driver of the freight train suffered the worst injuries among them with a broken thigh. Four passengers were also slightly injured. The railway line had reopened by afternoon and experts are investigating the cause of the crash, with initial assessments indicating that one of the trains had gone through a red light.