The mayor of Brazil's largest city, São Paulo, has said its health system could collapse as demand grows for emergency beds to deal with coronavirus cases.
Bruno Covas said the city's public hospitals had reached 90% and could run out of space in about two weeks.
São Paulo is one of the country's worst-hit regions, with almost 3,000 deaths so far.
On Saturday, Brazil overtook Spain and Italy to become the nation with the fourth largest number of infections.
The health ministry reported 7,938 new cases in the past 24 hours, taking the total above 241,000. Only the US, Russia and the UK have higher numbers.
The death toll in the Latin American nation over 24 hours was 485, meaning that the total number of deaths is 16,118 - the world's fifth-highest figure.
Health experts in Brazil have warned that the real number of confirmed infections in the country may be far higher than the official records, due to a lack of testing.
Brazil's far-right president Jair Bolsonaro has been strongly criticised both at home and abroad for his handling of the country's escalating coronavirus crisis.
He defied global health advice on social distancing on Sunday when he posed for photographs with supporters and children in the capital, Brasília.
Mr Covas said he was now in crisis talks with the state governor over introducing a strict lockdown to try to slow the contagion before hospitals were overwhelmed.
The governor of São Paulo state controls the police, and his support will be essential if a lockdown is to succeed.
São Paulo has the population of about 12 million, and official figures show that the majority of residents have been flouting social distancing rules.
The far-right president is popular in São Paulo, and he has argued repeatedly that distancing will only wreck the economy.
Mr Bolsonaro continues to oppose lockdown measures. He has downplayed the virus as "a little flu" and has said the spread of Covid-19 is inevitable.
In April, Mr Bolsonaro joined protesters demanding that lockdown restrictions be lifted. He says the restrictions are damaging the country's economy, bringing unemployment and hunger.
Last week, Brazilian Health Minister Nelson Teich resigned after less than a month in the job. Mr Teich stepped down after he had publicly criticised a decree by Mr Bolsonaro allowing gyms and beauty parlours to reopen. Mr Teich's predecessor was sacked after disagreeing with Mr Bolsonaro.
In the face of mixed messages, and with little government help at hand, not enough Brazilians are staying at home to slow the spread of the virus, the BBC's Americas editor Candace Piette says.