Some patients suffered minor injuries in the rescue operation in the fire that broke out on the second floor of the Metro Hospital and Cancer Institute, they said.
The fire started in an air conditioning vent and then spread to other floors, a senior police officer said.
A senior officer from the Delhi Fire Services said a call was received at 3.20 PM alerting them about the blaze, which intensified in the next 20 minutes. Twelve fire tenders were rushed to the spot, he said.
Police said that the 84 patients were safely evacuated from the hospital and shifted to its Noida branch.
The cooling operation was underway, the police said, adding that some patients suffered minor injuries in the episode.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.