At least 13 people died and 15 were injured in an explosion caused by a leakage in a cooking gas cylinder at a house in Mau on Monday, officials said.
The house in Walidpur area collapsed while two adjoining ones were extensively damaged due to the impact of the explosion which occurred around 7 am, police said.
The loud bang shook the neighbourhood, prompting people to rush out of their homes in panic.
The blast took place at the house of Chhotu Vishwakarma, who died around 10 years ago. His widow and five daughters were staying in the house, the police said.
Chhotu's three daughters -- Mona, 20, Mamta, 18, and Sanjana, 15 -- died while the remaining family members are missing, they said.
Prima facie, the blast was triggered by a possible leakage in the cooking gas cylinder, Inspector General (Law and Order) Praveen Kumar said in Lucknow.
Due to the intensity of the blast, the roof of the house collapsed.
Two adjacent houses were also badly damaged, he said, citing the initial report by Mau Superintendent of Police Anurag Arya.
Four family members of Kanhaiya Vishwakarma, whose house stood next to Chhotu's, also died in the blast, the police said.
They said it was not immediately known how the deceased -- Reena, Sarita, Sonam and Simpi -- were related to Kanhaiya.
Another neighbour Surendra Vishwakarma and his daughter Nidhi, 10, also died in the explosion, the police said.
Four passers-by -- Imtiyaz, 25, Zeehsan, 15, and Yasir, 13, and Shivam -- also died in the blast, they said.
The injured are undergoing treatment at district hospitals in Mau and adjoining Azamgarh, they added.
Immediately after getting news about the blast, Chief Minister Yogi Adityanath directed the Mau district magistrate and SP to rush all help to the injured, Additional Chief Secretary (Home) Awanish Awasthi said.
Adityanath also expressed his condolences to the family of the deceased, he said.
Speaking to reporters outside the Mau district hospital, cabinet minister Anil Rajbhar said, "It is a sad incident. A house has been completely destroyed. The state government is with the aggrieved family. Every possible medical help will be given to the injured."
A pall of gloom hung over Walidpur. Residents said it would be a dark Diwali for them this year.
A large crowd of onlookers gathered in the area as rescue operations were underway. Cranes and gas cutters have been pressed into service to remove the debris.
A team of the National Disaster Response Force too has been rushed to the blast site.
To prevent further loss of lives, the neighbourhood has been vacated as some houses developed cracks due to the explosion, the police said.