Four men were killed and three people injured and hospitalized in a fire that gutted a two-story mahjong game parlor in Hamamatsu, Shizuoka Prefecture, early Tuesday, local police said.

The police are looking into the possibility of arson in connection with the fire that broke out at around 3:35 a.m., investigators said.

An investigation has been launched, including a possible link with another fire, also a case of suspected arson, on Oct. 14 that burned part of the outer wall and used tires on the premises.

Police initially discovered the bodies of three men, thought to be customers, at the site near JR Hamamatsu Station, and another man was later confirmed dead after being brought to a hospital.

Police are trying to confirm the identities of the dead.

All seven were on the second floor of the building at the time of the fire, according to the police.