The deceased were driver Md Rubel, son of Shahab Uddin of village Charshita of Ramgati upazila of the district and passenger Abul Kalam, son of Jakir Hossain, and a painter by profession, of Sahapur area under Lakshmipur municipality.
The injured identified as Abul Hossain and Nayeem who are undergoing treatment at Noakhali Sadar Hospital.
Witnesses said that the gas cylinder exploded when the bus was taking fuel from one Green Leaf Filling Station in Muktiganj area at about 3:50am, leaving the four critically injured.
Of them, Kalam died on the spot and the bus driver died from his injuries on the way to Dhaka, said Joynal Abedin, a physician of Lakshmipur Sadar hospital.
The injured were shifted to a Noakhali hospital, he said.
Deputy commissioner Rajib Kumar Sarkar and superintendent of police Aktar Hossain visited the spot in the morning.
The DC said a probe body would be formed and financial assistance would be provided to the victims’ families.
Earlier on October 14, three people died and nine others sustained injuries in a gas cylinder blast in a bus in the district.