The incident took place near the venue of Congress leader Harminder Singh Jassi's roadshow.
Fatehveer Singh was rescued at around 5.30 am by National Disaster Response Force personnel, officials said.
While eight children were taken out safely by people working in nearby fields, four, including a girl three-year-old girl, were charred to death, they added. Punjab CM Amarinder Singh ordered a magisterial enquiry into the incident.
Kejriwal blames Sukhbir Badal for blast, while Sukhbir, Amarinder blame the AAP chief for it.