More than 70 patients with COVID-19 infections in the private hospital, on the third floor of the mall, were evacuated to other centers, local civic officials said.
Speaking to reporters outside the hospital, the chief of Western Maharashtra State, Uddhav Thackeray said "the shops on the floor below the hospital caught fire."
He added that "it took some time to move the patients on ventilators and that is why they died."
Mumbai is struggling through the worst phase of its COVID-19 pandemic, and reported more than 5,500 cases in a day on Thursday (March 25), its highest number since the outbreak began.
Meanwhile, India's new coronavirus infections rose 59,118 overnight, the highest daily rise since October 18, health ministry data showed on Friday (March 26).
The country's overall caseload stood at 11.85 million.