Firefighters, police and ambulances were called to Mallowdale Avenue in the town in the early hours of Sunday.
Two houses had collapsed and a third property was seriously damaged, Lancashire Police said.
George Arthur Hinds was described by his parents, Vicky Studholme and Stephen Hinds, as their "beautiful little angel."
Ms Studholme and Mr Hinds were also injured in the blast, which happened at 02:40 BST.
Another man and woman remain in hospital in critical condition, Lancashire Police said.
