SEOUL, South Korea (CNN) -- A fire at a boarding house early Friday killed five men and one woman, injuring 11 other people, South Korea's Yonhap news service reported.
Four were in critical condition, Yonhap said.
The boarding house occupied the 9th floor of a 10-story building in Yongin City, about an hour's drive from Seoul, Yonhap reported.
Police and fire officials said they suspect someone may have set fire to the rooms one after the other, Yonhap reported.
Each of the 68 rooms on the floor is about 6.6 sq. meters (yards).
Fire officials said the blaze started at about 1:20 a.m. and was extinguished shortly after 2 a.m., but the maze of corridors kept firefighters from reaching all 40 people who were sleeping there at the time.
All About South Korea
From the Blogs: 
Sit tight, we're getting to the good stuff
