The blast took place in the LPG cylinder filling shop located on the ground floor of Zacha Bacha Hospital area along Mir Nabi Bux Town Road in UC-8 of Neerunkot town.
The children who succumbed to their injuries were identified as Bilal, 15, Raheem, 5, Hasnain and Ayan, 1122 officials said.
At least 60 people, mostly children, received serious burn injuries and had to be shifted to Karachi after being provided emergency treatment at the Liaquat University Hospital (LUH).
Some 18-22 injured persons with 80pc to 90pc burns were referred to a major hospital in Karachi.
Those who were shifted to Karachi, according to LUH record, are Azam, 7, son of Rais, Bilal, 11, son of Asif, Azam, 9, son of Shakir, Hasnain, 7, son of Rasheed, Ali Raza, 2, son of Bilal, Abdul Hadi, 14, son of Asghar, Zulfiqar, son of Mohammad Umer, Akram Shah, 38, son of Qurban Shah, Raeesudin, 35, son of Alamuddin, Ali, son of Zeeshan, Akram, 50, son of Waseem, Abbas, Dodo 25, and Faizan, 40, son of Ishaq.
Sindh Chief Minister Syed Murad Ali along with ministers visited Burns Ward and inquired about the health of injured persons.