Umesh Tripathi, a medical official, added that more than 150 people were admitted to hospitals after the crush and that the death toll could still rise.
Unverified videos showed dozens of bodies, many of them women, piled up on the ground outside a local hospital.
Ashish Kumar, Hathras district administrator, told reporters: “The incident happened due to overcrowding at the time when people were trying to leave the venue.”
An unidentified witness told broadcaster India Today that there was a narrow exit at the venue: “As we tried to exit towards a field, suddenly a commotion started, and we didn’t know what to do.”
Shakuntala Devi, another witness, said: “When the sermon finished, everyone started running out.
“People fell in a drain by the road. They started falling on top of the other and got crushed to death.”
‘Overcrowding may be factor’
Police said overcrowding may have been a factor. Initial reports suggested that over 15,000 people had gathered for the event, which only had permission to host about 5,000.
Uttar Pradesh is India’s most populous state with more than 200 million people. Yogi Adityanath, chief minister, ordered an investigation.
“Instructions have been given to the concerned officials to conduct relief and rescue operations on war footing and to provide proper treatment to the injured,” he said.
Deadly stampedes are relatively common during Indian religious festivals, where large crowds gather in small areas with few safety measures.
In 2013, pilgrims visiting a temple for a popular Hindu festival in central Madhya Pradesh state trampled each other amid fears that a bridge would collapse, and at least 115 were crushed to death or died in the river.
In 2011, more than 100 Hindu devotees died in a crush at a religious festival in the southern state of Kerala.