A string of explosions involving what appeared to be butane gas occurred at Seoul\'s two major transportation hubs Thursday, prompting police to launch a terrorism probe. No one was hurt or killed in the explosions at Seoul Station in the central part of the capital and Seoul Express Bus Terminal in southern part of the city, Yonhap quoted police as saying. The explosives appeared to be homemade and had been placed inside lockers set up at the train and bus stations for public use, the police said. The explosions occurred about half an hour apart. The police have evacuated the areas and are tracing a man who they said was seen on a surveillance camera putting a package inside the locker at Seoul Station. Only the explosives at the express bus terminal went off with a boom, they said.