An express train in Japan derailed and caught fire inside a tunnel overnight, injuring 39 passengers, railway officials said on Saturday. The injured were taken to hospital for treatment of smoke inhalation and burns. None of them were seriously injured, officials said. The train, carrying 240 passengers, made an emergency stop inside a tunnel on the northern Hokkaido island on Friday after its driver noticed smoke emerging from the train. The passengers escaped but the fire continued to burn until early on Saturday morning, destroying the six-carriage train. Officials and emergency workers found marks on the track and said one of the carriages had apparently derailed just before entering the tunnel. Police and the train operator are looking into the cause of the accident.