South Korean President Moon Jae-in comforted mourners in the small scenic city of Jecheon on Friday amid growing public anger at how fire ripped through an eight-story building, killing at least 29 people, most of them taking a sauna.

All but one of the victims had been identified by Friday morning, including 20 women who were overcome by toxic fumes in the second-floor sauna, Jecheon fire chief Lee Sang-min said.

"Our crew on the scene said the lockers inside the facility were installed like a labyrinth and it's a glass building with few windows, which apparently made way for the smoke from the first floor to quickly fill up the second floor," Lee told reporters.