Three women, all students at the University of New Hampshire, remained hospitalized Sunday after suffering serious burns to their feet when a hot-water pipe burst Saturday, flooding their residence hall at the Durham, N.H., school. The students were injured while evacuating Hunter Hall. The decades-old pipe had been leaking for an undetermined amount of time before failing, the university said in a statement. The two hot-water pipes leading into the building were repaired Sunday and heat was restored to the hall around 3 p.m., the university said. The injured students were taken to local hospitals, then transferred to Boston hospitals.