A fire broke out at a hotel in the South Korean city of Bucheon on Thursday, killing at least seven people and injuring 12 others, officials said.

Kim In-jae, the director of Bucheon’s public health department, said at a briefing that three of the injured people were in serious condition. The injured were being treated at six nearby hospitals.

Lee Sang-don, an official with the Bucheon Fire Station, said the nine-story hotel had 23 guests when the fire broke out Thursday evening.

Lee said the fire, which began on the eighth floor, was extinguished as of Thursday night. The cause was being investigated, he said.

The victims were found scattered in halls and stairways, and the number could increase as emergency workers search the building, Lee said.

More than 150 firefighters and 46 vehicles were deployed to put out the fire.