At least 25 people have died in a cold  snap sweeping across northern India, the BBC reported.  The majority of deaths were in the state of Uttar Pradesh.  Rajasthan, Punjab and Haryana are among the other northern states  badly hit. Most deaths were among homeless and elderly people.  Heavy fog has disrupted flights and train services out of the  capital, Delhi, and neighboring states. The capital Delhi is also affected by the cold spell, with  temperatures dipping to 7C and fog disrupting flight schedules. Dense fog has also affected train services and flights in Rajasthan,  where temperatures fell to 3.8C. An official from the India Meteorological Department said the cold  weather would continue for a number of days.