Officials across India are searching for hundreds of people who attended a religious event in the capital that has set off several Covid-19 clusters.
At least six regions have reported cases that can be directly traced to the days-long congregation at a mosque.
Delhi officials are now clearing the building, where more than 1,000 people have been stranded since the government imposed a lockdown last week.
At least 24 have tested positive so far, the state health minister said.
They are among some 300 people who showed symptoms and have been moved to various hospital to be tested, he told the media. Another 700 have been shifted into quarantine centres, he added.
It is believed that the infections were caused by preachers who attended the event from Indonesia.
State officials have called for action to be taken against mosque officials, but they have denied any wrongdoing.
Local media reports say that Nizamuddin - the locality where the mosque is located - has been cordoned off and more than 35 buses carrying people to hospitals or quarantine centres.
The congregation - part of a 20th Century Islamic movement called Tablighi Jamaat - began at the end of February, but some of the main events were held in early March.
It's unclear if the event was ticketed or even if the organisers maintained a roster of visitors as people attended the event throughout, with some staying on and others leaving. Even overseas visitors, some of them preachers, travelled to other parts of the country where they stayed in local mosques and met people.
So officials have no easy way of finding out how many people attended the event or where they went. But they have already begun to trace and test.
The southern state of Telangana reported on Sunday night that six people who had attended the event died from the virus. The state's medical officer told the BBC that more than 40 of Telangana's 71 cases were either directly or indirectly linked to the event.
Indian-administered Kashmir reported its first death from the virus last week - a 65-year-old who had been in Delhi for the congregation. Officials told BBC Urdu that more than 40 of the region's 48 cases could be traced back to that one patient.
A cluster has even appeared in the distant Andaman and Nicobar Islands, where six of the nine who have tested positive, had returned from the Delhi event.
The southern states of Tami Nadu, Telangana and Andhra Pradesh have said more than 3,000 people from their states had attended the event, and Tamil Nadu has traced 16 positive patients to it.
States have also asked other people who attended to come forward for testing.
Delhi Chief Minister Arvind Kejriwal has asked for a police complaint to be registered against the head of the mosque.
However, the event's organisers have issued a statement, saying they had suspended the event and asked everyone to leave as soon as Prime Minister Narendra Modi announced that there would be a day-long national curfew on 22 March.
While many were able to leave, they say, others were stranded because states began to seal their borders the following day, and two days later, India imposed a 21-day lockdown, suspending buses and trains.
The mosque's premises include dormitories that can house hundreds of people.
The organisers say they informed the local police about all of this and continued to cooperate with medical officers who came to inspect the premises.
The mosque, the statement says, "never violated any provision of law, and always tried to act with compassion and reason towards the visitors who came to Delhi from different states. It did not let them violate the medical guidelines by thronging ISBTs (bus stops) or roaming on streets."
This is not the first time religious congregations have been blamed for the spread of coronavirus.
Tablighi Jamaat events have also been blamed for spreading cases in Indonesia and Malaysia.
And in South Korea, many positive cases were linked to the Shincheonji church, a secretive religious sect, that has since apologised for its role in the outbreak.