Thirteen women and children, all girls, died after falling into a well while performing a marriage ritual in Uttar Pradesh's Kushinagar district, police said on Thursday.
The incident, in which at least 10 people were also injured, took place at Naurangiya Tola village when an iron grille, they were sitting on, broke, they said.
Chief Minister Yogi Adityanath and Prime Minister Narendra Modi have expressed grief over the incident.
On Wednesday night, the pre-wedding ritual of "haldi" was being performed. Some women and children were sitting on the iron grille and it suddenly broke and fell into the well, District Magistrate S Rajalingam said.
At least 10 people were also injured in the incident at the village under the Nebua Naurangiya police station area, he said, adding that they have been hospitalised.
According to information received so far, 13 people have died -- Pooja (19), Shashi Kala (15), Shakuntala (35), Mamta Devi (35), Meera (25), Pooja (20), Pari (1), Jyoti (15), Radhika (16), Sundari (15), Aarti (10), Pappi (20) and Manu (18), officials said.
They said that an assistance of Rs 4 lakh will be to the family of each the deceased.
The bodies have been sent for post-mortem and the case is being investigated, Rajalingam said.
Condoling the loss of lives, Prime Minister Mod described the incident as heart-rending.
He extended his condolences to the families of victims and wished a quick recovery for the injured. The local administration is offering all possible help, Modi said in a tweet.
Directing officials to provide all assistance, Adityanath tweeted, The death of villagers in an unfortunate incident in Naurangiya Tola village of Kushinagar district is very sad. My condolences are with the bereaved families of the deceased. Prabhu Shri Ram is wishing for the speedy recovery of the injured.
According to a state government spokesperson in Lucknow, the chief minister has directed officials of the district administration to ensure proper treatment to the injured people.