Why are Delhi borders sealed during unlock 1?

Since the commencement of unlock 1, many relaxations have been given to the residents of India. Delhi also acted similarly and provided many relaxations to the people like resumption of salon services, opening up of markets, traveling via auto and taxis has been allowed too but the borders are

source https://news.abplive.com/videos/news/india-why-are-delhi-borders-sealed-during-unlock-1-1249608