Firefighters extinguish a fuselage fire on an Air Busan aircraft, originally bound for Hong Kong, at Gimhae International Airport, Jan. 28. Yonhap

The number of victims injured in an airplane fire at a Busan airport the previous day has risen to seven, all with minor injuries, fire authorities said Wednesday.

On Tuesday night, an Air Busan plane bound for Hong Kong caught fire at its tail while preparing to take off from Gimhae International Airport in Busan, some 320 kilometers southeast of Seoul, prompting all its 176 passengers and crew members to evacuate.

Fire authorities in Busan said Wednesday that seven people were receiving treatment at hospitals for injuries sustained in the fire.

Authorities had initially reported the number of casualties as three but revised the tally after further examinations.

Four of the victims were crew members who complained of chest discomfort due to smoke inhalation, while the three others — a woman in her 70s and two in their 50s — complained of pains in their tailbones and backs.

Gimhae International Airport was operating normally as of Wednesday, with all 279 flights scheduled for the day running as planned, except for eight Air Busan flights that were canceled.

Also on Wednesday, acting President Choi Sang-mok instructed officials to thoroughly investigate the fire accident and take prompt response measures.

"As many flights operate at Gimhae Airport, I urge proactive efforts to ensure the safe operation of airplanes and prevent any inconveniences to the public," the government said in a press release, quoting him.

According to fire authorities, passengers who had boarded the plane reported seeing a fire start in a baggage compartment, accompanied by crackling sounds and smoke.

Some have speculated that an external battery or an electronic device packed inside a suitcase could be the source of the fire, as an investigation was under way to determine the cause.

Firefighters extinguish a fire in the fuselage of an Air Busan aircraft, originally bound for Hong Kong, at Gimhae International Airport, Jan. 29. Yonhap

While a joint team of firefighters and transportation ministry officials has been tasked with determining the cause of the fire, police plan to examine whether any entities, such as the air carrier, should be held responsible for professional negligence resulting in injuries.

Police plan to review regulations on carry-on luggage acceptance and electric power facilities inside the affected plane as part of their investigation.

Police are also expected to consider the possibility of terrorism, though a police official said that no signs of terrorist involvement have been detected so far. (Yonhap)

Authorities inspect an Air Busan aircraft at the Gimhae International Airport in Busan, Jan. 29, after it caught a fire the night before. Yonhap