A government inquiry has been ordered into what led to a stampede that killed at least 36 people at a train station in the northern Indian city where millions of devout Hindus have gathered for a religious festival, officials say.
More than 40 million people were in Allahabad on Sunday to mark the Kumbh Mela, a Hindu religious festival.
People thronged to the main hospital in the city on Monday to see if their relatives were among the 36 dead and 30 people injured in Sunday evening's stampede at the train station. Tens of thousands of people were in the station waiting to board a train when railway officials announced a last-minute change in the platform, triggering the chaos.
Mohammed Azam Khan, the head of the festival's organising committee, resigned from his post on Monday "on moral grounds".
Police denied they had used batons to control the crowd.
Pawan Kumar Bansal, India's railways minister, said that an inquiry has been ordered into what led to the stampede.
The chief medical officer of Allahabad district said the death toll rose to 36 after 14 more people died during treatment, the Press Trust of India and NDTV news channel said.
Dr P Padmakar, the medical superintendent of the main state-run hospital, said 23 of the 36 people killed were women.
Tens of millions of Hindus had gathered for a holy bath in India's sacred Ganga River for the most auspicious day of the world's largest religious festival, Kumbh Mela.
The population of the city had swollen from its normal 1.2 million to about 40 million on Sunday morning, with about 20 million packed inside the vast sealed-off bathing area on the banks of the river, Ashok Sharma, a government spokesperson, said.
Amid the crush, the thousands of volunteers on duty and police were urging pilgrims to take one short dip and then leave the freezing waters to make space for others behind them.
"Aerial surveys by choppers, flying cameras and our estimates put the figure at around 20 million people taking a holy dip in the rivers," Sharma told the AFP news agency on Sunday.
The Maha Kumbh Mela, which began last month and ends in March, takes place every 12 years in Allahabad. Smaller, similar events are held every three years in other locations around India.
The bathing takes place at an area called Sangam, the confluence of the rivers Ganga and Yamuna and a third mystical waterway called the Saraswati.
Devotees believe entering the mighty rivers cleanse them of sin and free them from the cycle of rebirth.
Assorted dreadlocked holymen, seers and self-proclaimed saints from all over the country have assembled for the spectacle that offers a rare glimpse of the dizzying range of Indian spiritualism.
More than 7,000 policemen had been deployed to oversee the Sunday bathing ritual, along with 30,000 volunteers, police say.
Management of the festival requires a monumental effort - and a budget of $290m.
Thousands of buses and special trains were ferrying people to Allahabad where the heavily polluted Yamuna river flows into the Ganga.