Ashma (40) and Ajay (16) died on the spot while Ashma's husband Yasin, her son Dilshad and neighbour Vijay suffered severe burn injuries, they added.
The incident happened when Ashma was cooking food in her hut, police said.
Dilshad has been admitted to a local hospital while Yasin and Vijay were sent to a hospital in Lucknow due to their critical condition.