Daily infections rose by 382,315 on Wednesday, health ministry data showed. Government modelling had pointed to a peak by Wednesday, a few days earlier than thought, since the virus has spread faster than expected.
The surge of the highly infectious Indian variant of the coronavirus has seen hospitals runs out of beds and oxygen and left morgues and crematoriums overflowing. Many people have died in ambulances and car parks waiting for a bed or oxygen.
Two "oxygen express" trains reached the capital Delhi on Wednesday carrying desperately needed liquid oxygen, Minister of Railways Piyush Goyal said on Twitter. Over 25 trains have so far delivered oxygen to different parts of India.
India's government says there are enough oxygen supplies but distribution has been hindered by transport problems.
India has an estimated 3.45 million active cases, but medical experts say the actual numbers of dead and infected could be five to 10 times higher. The country added 10 million cases in just over four months, after taking more than 10 months to reach the first 10 million.
Daily testing in India has fallen sharply to 1.5 million, state-run Indian Council of Medical Research (ICMR) said on Wednesday. It hit a peak of 1.95 million on Saturday.