Amazonas state in northern Brazil on Thursday announced a 10-day curfew to try to slow the spread of the coronavirus, as cases soar and hospitals run out of beds and oxygen.
Authorities warned of a dire situation across the vast state. In its capital Manaus, the health system has been pushed to breaking point.
The city has "run out of oxygen and some health centers have become a type of suffocation chamber," Jessem Orellana, from the Fiocruz-Amazonia scientific investigation institute, told AFP.
"Here there aren't any empty beds left, any oxygen tanks, nothing -- all we have left is faith," Manaus resident Luiza Castro told AFP.
Amazonas governor Wilson Lima said the state was "in the most critical moment of the pandemic."
The 7:00 pm to 6:00 am curfew will begin Friday.
"These are difficult but necessary measures," Lima said. "We are in a war operation."
According to official figures, Manaus on Wednesday saw a fourth straight day of record burials -- 198, with 87 of them deaths from Covid-19.
Oxygen is needed to treat Covid-19 patients suffering from respiratory complications.
Amazonas produces "significant quantities of oxygen, but now our people need oxygen and solidarity," said Lima, who added some patients would be transferred to other states.
Military personnel delivered 400 oxygen cylinders to Amazonas over the last five days.
Brazil has recorded more than 205,000 deaths from Covid-19, second only to the United States.
The national average is 98 deaths per 100,000 inhabitants, but in Amazonas the figure is 142 per 100,000, surpassed only by Rio de Janeiro (158) and Brasilia (145).
An expert studying coronavirus mutations in Amazonas told AFP a new strain detected in the state is "very probably" more contagious than the original virus, just like new strains found in Britain and South Africa.
Felipe Naveca said the variant, which the World Health Organization described as "worrying," may have spread throughout Brazil and could already be the dominant strain in Amazonas.
The worsening situation in Manaus was not due only to one variant, he added, noting that authorities were expecting a rise in virus cases due to end-of-year parties.
"We need urgent support from the population to reduce the transmission and slow down the virus's evolution," Naveca said.
Experts worry new mutations could eventually show resistance to the vaccines developed to combat the original strain.
However, "right now there's no evidence that this line prejudices the vaccine's response," Naveca said, and Brazil aims to start its vaccination campaign sometime this month.
There is concern, though, the new variant could already have spread throughout Brazil, and it has been detected as far afield as Japan.
Britain on Thursday said it was suspending all arrivals from South America due to the new coronavirus variant.