OSAKA — A man in a work uniform appeared to be cleaning near automated teller machines in an office building Tuesday evening about five minutes before an explosion there left one man in critical condition and three others injured, police said Wednesday.

The bank said it had assigned no one to clean the area Tuesday.

The explosion and subsequent fire occurred at around 6:45 p.m. Two ATMs operated by Asahi Bank and the surrounding area on the first floor of the nine-story Osaka Saitama Building were damaged. The building is in the busy business district of Chuo Ward.