The incident took place while wedding preparations at the house of a man named Lallan were on in Rafipur village under Deva police station area. The small cylinder exploded injuring 15 persons, police said.
The injured were shifted to Civil Hospital in Lucknow where Sonam (3), her brother Aditya (4), Khushi (3), Golu (4), his brother Vivek (3), Gyanwati (45) and Kalawati (60) succumbed, police said.
The other injured are undergoing treatment in the hospital where the condition of two was stated to be critical, police said, adding a case has been registered.