The incident occurred when a large number of people were praying in the mosque at Rehmat Colony in Mian Channu area.
Five persons were killed and 50 others injured, state-run APP news agency reported.
The injured were taken to hospital. Five of them in a critical condition were transferred to Nishtar Hospital in Multan.
Women and children were reciting the Quran in the upper storey of the mosque at the time of incident.