NEW DELHI >> As India expanded its virus-containment measures and halted its train network, the country’s lifeblood, the federal government warned today of strict legal action for those who flout the rules.

The wholesale shutdown of India’s massive train system is unprecedented.

“Please save yourself, save your family,” Prime Minister Narendra Modi tweeted in Hindi, calling for states to follow the preventive measures issued by the federal government to contain the spread of the virus.

The strict legal action vowed wasn’t immediately clear. Other places have simply sent violators home, since alternatives like detention would create crowded conditions where the virus could spread.

To contain the outbreak, authorities have gradually started to lock down much of the country of 1.3 billion people, sending stock markets to record lows. Parliament adjourned its session, and India’s civil aviation authority banned all commercial flights within India starting Wednesday. International flights were kept from landing from Sunday until at least March 31.

At least 80 districts where cases of infection have been detected are under stringent lockdown. Police and health care were operating, but commercial establishments have closed except for essential services. Banks have asked their customers to switch to online transactions and reduced their office staff.

The government has fervently appealed for people to practice social distancing and wash their hands often.

But Modi’s call for a 14-hour voluntary curfew on Sunday was the first nationwide effort at social isolation practices the World Health Organization believes are critical to slowing the outbreak to a level that doesn’t overwhelm health care systems. Lockdowns in other places have lasted at least two weeks, which is believed to be the maximum incubation period of the virus.

Streets across India’s cities on Sunday were deserted as citizens stayed indoors heeding Modi’s call. But key train stations were packed with thousands of migrant workers suddenly out of work and trying to head to their villages, risking carrying the infection to the nation’s vast hinterland.

Late Sunday, train services were suspended until March 31 while crowds were still waiting to board. The suspension included major long-distance trains and public transit in India’s big cities, exempting only freight. The New Delhi Railway Station, usually teeming with activity, was empty on Monday.

India’s national railway system totals 67,000 kilometers (42,000 miles) and carries more than 8 billion passengers a year.

India has at least 415 active cases of infection with the new coronavirus and seven deaths from COVID-19, the illness it causes.

Many were linked to foreign travel, but indigenous spread of the disease is considered inevitable in India, where tens of millions live in dense urban areas with irregular access to clean water.

Experts have said the number of confirmed cases seemed low for the world’s second-most populous country, amid concerns that India is not testing enough people. The bulk of the testing had been aimed at international travelers and their contacts, but in recent days the government has expanded it to people in hospitals with respiratory symptoms such as pneumonia.

“Our biggest challenge is how do we break this chain of transmission,” Lav Agarwal, a senior health ministry official, said at a briefing in New Delhi on Sunday.