The veteran BJP leader was brought to AIIMS in a critical condition after suffering a heart attack but soon passed away, the sources said.
"She was brought to AIIMS at 9.35 p.m.. We gave her CPR as well. She passed away at 10 p.m.," said the source.
Union Ministers Rajnath Singh, Nitin Gadkari, Prakash Javadekar, and Harsh Vardhan, and BJP Working President J.P. Nadda arrived at the hospital as they got the news.
Her body has been taken to her residence from the AIIMS.
Leaders from across the political spectrum condoled the death of Sushma Swaraj, who had also been the first woman Chief Minister of Delhi.
Prime Minister Narendra Modi said that a "glorious period in Indian politics" had ended and recalled her efforts as External Affairs Minister in his first government in helping any Ind abroad in any trouble.
"An excellent administrator, Sushma Ji set high standards in every Ministry she handled. She played a key role in bettering India's ties with various nations. As a Minister we also saw her compassionate side, helping fellow Ind who were in distress in any part of the world.
"A glorious chapter in Indian politics comes to an end. India grieves the demise of a remarkable leader who devoted her life to public service and bettering lives of the poor. Sushma Swaraj Ji was one of her kind, who was a source of inspiration for crores of people," he said in a series of tweets.
Congress leader Rahul Gandhi, West Bengal Chief Minister Mamata Banerjee, Delhi's Deputy Chief Minister Manish Sisodia were among those who condoled her death.
( With inputs from IANS )