Modi asked India's 1.3 billion people to stay at home on Sunday, but also to collectively cheer front-line health care workers at 5 p.m.
Shortly before 5, the cacophony in New Delhi, the capital, began as people on balconies and rooftops clapped, rang bells, banged pots and pans, played music recordings and exploded fireworks, sending crows and parakeets streaming from treetops, and stray dogs and cows into the deserted streets.
At least 341 people have been infected in India by the new coronavirus, including the first case in the largely impoverished eastern state of Bihar, according to health officials. Five people have died in the country from COVID-19, the illness caused by the virus.
Earlier Sunday, thousands of people from Mumbai and elsewhere in the western state of Maharashtra, which has confirmed the highest number of cases in India, jostled at a railway station in the city of Prayagraj in Uttar Pradesh, India's most populous state. Police struggled from a distance to control the crowds, who were waiting to be taken to their villages by buses and taxis that appeared unlikely to come.
"We are playing with our health by crowding railway stations and bus stands," Modi said in a tweet.
Indian Railways later suspended all passenger train services until March 31, although freight services will continue. It was unclear what this would mean for people stranded at railway stations.
In recent days, migrant workers hauling backpacks have swarmed overcrowded trains across many Indian cities, an exodus among panic-stricken day laborers that has sparked fears the virus could spread to the countryside.
The typical bustle of New Delhi, meanwhile, was otherwise silent on Sunday, with nearly empty buses and taxis plying the city's lightly trafficked roads, gates to public gardens, temples and churches locked, and building guards with scarves tied around their faces seated outside on plastic chairs watching empty streets.
A road in New Delhi near a Sufi shrine where hundreds of pilgrims often camp was empty except for an occasional passing car.
Most businesses were to be closed Sunday except for essential services like hospitals.
While some Indian states — including Maharashtra — had already issued stay-in-place orders and closed borders, Sunday marked the first nationwide effort at social isolation practices that the World Health Organization believes are critical to flattening the infection curve worldwide.
No commercial airplanes from abroad are allowed to land in India for a week starting Sunday.
Officials said 23 people have recovered from COVID-19, and have not documented any community spread in India.
While the coronavirus can be deadly, particularly for the elderly and people with other health problems, for most people it causes only mild or moderate symptoms, such as fever and cough. Some feel no symptoms at all and the vast majority of people recover.
India's government has made fervent appeals to the public to practice social distancing and good hand hygiene. India also was one of the first countries to essentially shut its borders and deny entry to all but a select few foreigners.
However, experts have said indigenous spread of the disease in India, where tens of millions live in dense urban areas with irregular access to clean water, is inevitable.