A firefighter checks the cars destroyed by a fire after an electric vehicle exploded inside an underground parking lot of an apartment complex in Incheon, Friday. Yonhap

A blaze caused by an electric vehicle battery that left some 140 cars damaged and 23 people hospitalized in Incheon on Thursday has raised safety concerns about lithium-ion batteries.

According to the Incheon Fire Department, Friday, it took more than eight hours to put out the fire that started following an explosion of what appeared to be a Mercedes-Benz EQE model inside an underground parking lot of an apartment complex in the city's Cheongna International City.

As a result, 140 vehicles were destroyed or blackened and at least 23 people received hospital treatment for smoke inhalation. With a prolonged power outage caused by the fire, at least 121 people from 46 households were staying in temporary shelters set up at welfare centers near the apartment complex as of Friday morning.

Surveillance footage showed smoke coming out of the vehicle before it suddenly burst into flames. The car was not being charged at the time of the explosion, according to firefighters.

After receiving emergency calls, the fire department mobilized more than 170 firefighters as well as fire trucks and other equipment to extinguish the ensuing blaze. Their effort was hampered by narrow pathways to the fire source below ground. In the meantime, hundreds of residents evacuated from adjacent buildings.

In cooperation with the police, firefighters are looking into the exact cause of the explosion.

The fire case is the latest one believed to have been caused by lithium-ion batteries, which are used in many commercial products including electric cars, electric bikes, energy storage systems and toys among many others.

Lithium-ion batteries are known to be highly sensitive to high temperatures and are inherently flammable. Given that they have a high energy density, these fires can spread quickly and are difficult to extinguish.

According to research on fires caused by lithium-ion batteries, most such fires occur when the battery is being charged. But that's obviously not the reason for the Incheon case. It can also be caused by product defects or other factors.

Mercedes-Benz Korea expressed "deep regret" over the parking lot fire and vowed to fully cooperate with investigators in a statement sent to Yonhap, a Korean news agency.

However, the company refused to comment when asked to identify the model that is being investigated and which battery had been installed in that car.

"As the investigation is still ongoing, we ask for your understanding that we cannot provide further details at this time," the company said.

According to data from the National Fire Agency, the number of fires caused by electric vehicles has been on the rise in recent years, from just three in 2018 to 72 in 2023.

As electric cars continue to grow in number around the country, so too do concerns over the safety of their batteries.

To prevent similar accidents, a group of lawmakers, led by Rep. Song Eon-seog of the ruling People Power Party, proposed a bill on Friday to install more firefighting resources near EV charging systems in parking lots.