A major private hospital in Mumbai was shut to new patients and declared a coronavirus containment zone on Monday after 26 nurses and three doctors tested positive, an official said.
Since the virus hit India -- which has been under lockdown since March 25 with 111 deaths so far -- medical workers have complained about not being given adequate protective gear.
Mumbai city authority spokesman Vijay Khabale-Patil told AFP that the Wockhardt Hospital has been declared a "containment zone" after the cases were confirmed.
"Three hundred staffers have been quarantined and the hospital is shut," he told AFP.
The United Nurses Association (UNA) in Mumbai accused hospital management of failing to protect staff by refusing to let them wear appropriate safety gear.
"They told the medical staffers to wear simple (surgical) masks... and attend to the patient," said Akash S. Pillai, UNA general secretary for Maharashtra state, of which Mumbai is the capital.
"They were thinking that if the staff wore protective gear, family members of COVID-19 patients would get scared," he told AFP.
"Many well-known hospitals in Mumbai" were exposing their workers to the same risks, he said.
He added that Wockhardt waited too long to carry out tests on its staff, thereby increasing the possibility of infections spreading.
Wockhardt released a statement saying that the source was an asymptomatic 70-year-old patient who had suffered a cardiac emergency, adding that "hospital staff were unknowingly exposed to the infection in the time period" before the patient was tested for coronavirus.
The hospital did not directly address the allegations against management.
India has so far recorded over 4,000 coronavirus cases.
But experts caution the real numbers are likely to be far higher, with the country carrying out little testing of its 1.3 billion population.
Mumbai, home to 12.5 million people according to the 2011 census, has so far confirmed 458 cases, including five in the Dharavi area, home to one of Asia's biggest slums, and 30 deaths.