India has reported more than 300,000 new coronavirus cases in a 24-hour period - the biggest one-day total seen anywhere in the world since the pandemic began.
The country's health ministry said there had been 314,835 new cases on Thursday, a number that passes the previous record - 297,430 in the US in January.
The previous day, India had reported 295,041 new COVID-19 cases.
India's number of deaths rose by 2,104 to reach a total of 184,657.
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Prime Minister Narendra Modi said earlier this week that India was facing a coronavirus "storm" which was overwhelming its health system.
Hospitals are facing a severe shortage of beds and oxygen, with some private hospitals in Delhi warning they have less than two hours' supply of the gas.
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People have crowded into refilling facilities, trying to refill empty oxygen cylinders for relatives in hospital.
At least 22 patients in western India died on Wednesday when the oxygen supply to their ventilators ran out due to a leak.
There have even been instances of looting oxygen tankers.
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Mr Modi has been criticised for allowing big gatherings such as weddings and festivals where crowds can mix in confined spaces.
He has also addressed packed political rallies for local elections, speaking to millions of people.
Despite the fact that hospitals are struggling, Mr Modi said earlier this week that state governments should not impose a harsh lockdown.
Instead, he suggested micro-containment zones in an effort to avoid damaging the economy.
But the state of Maharashtra has strengthened its restrictions until at least the beginning of May.
All offices - except those providing essential services - must operate with no more than 15% of their staff.
Travel by private vehicle is only allowed for medical emergencies.
And only medical workers and government employees can ride on the trains.
So far, India has administered nearly 130 million doses of the vaccine but this is still a small effort when compared with its population of 1.35 billion.
Currently, only frontline workers and those aged above 45 are eligible but all adults are expected to be allowed a dose from May.
There could be delays ahead, with the country's Serum Institute warning that it will not be able to reach 100 million doses per month until July, compared with its previous forecast of late May.
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2:59
COVID-19: India 'in grip' of second wave
Analysis: A creaking public health system under threat
By Neville Lazarus, India reporter and producer
India is in the grip of a second wave which is out of control.
It has taken just 17 days for the daily numbers to rise from 100,000 to more than 300,000 at a rate of 6.76 % per day. This is more than four times faster than a similar rate in the United States.
Hospitals in the capital Delhi - and other cities - are running out of oxygen.
Many in Delhi have only a few hours of stock left and have appealed to the government for more.
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0:52
Patients dies after oxygen tank leaks
The low number of cases in the winter months had lulled people into believing the pandemic was over. The opening of markets, festivities - normality - a low fatality rate and, now, vaccinations, meant Indians let their guard down.
Millions of Hindu pilgrims have also congregated in Haridwar to celebrate the month-long Maha Kumbh festival.
Though it has now been scaled down and many religious congregations have left, the event has been called a super spreader by health activists.
India may have one of the lowest fatality rates in the world, but it can ill afford a severe burden on its already inadequate and creaking public health care system.
For decades, successive governments have spent just over 1.2% of its GDP on healthcare.
More than 70% of its citizens rely on expensive private healthcare and just one illness can push a family into poverty.
