Delhi and neighbouring Uttar Pradesh on Sunday recorded highest daily spike since the Covid-19 pandemic began in March last year.
Health authorities in the national capital said that the city recorded 10,774 fresh Covid-19 infections and 48 deaths.
The grim record comes on a day chief minister Arvind Kejriwal said the fourth wave is extremely dangerous.
Kejriwal said lockdown is a possibility if the "hospital system collapses" in the city.
In Uttar Pradesh, where the Yogi Adityanath government ordered shutting of schools till April 30, 15,353 people tested positive for the deadly virus.
67 fresh deaths pushed the toll to 9,152 in the most populated Indian state.