21 days lockdown.

With four hours’ notice, India’s prime minister announced that no one could leave home for 21 days — the most severe step taken anywhere in the war against the coronavirus

NEW DELHI — India’s prime minister ordered all 1.3 billion people in the country to stay inside their homes for three weeks starting Wednesday — the biggest and most severe action undertaken anywhere to stop the spread of the coronavirus.

“There will be a total ban of coming out of your homes,” the prime minister, Narendra Modi, announced on television Tuesday night, giving Indians less than four hours’ notice before the order took effect at 12:01 a.m.

“Every state, every district, every lane, every village will be under lockdown,” Mr. Modi said.

The breadth and depth of such a challenge is staggering in a country where hundreds of millions of citizens are destitute and countless millions live in packed urban areas with poor sanitation and weak public health care.