The explosion occurred in a building in Susukino, a bustling entertainment district in Sapporo, prompting a call to the fire department at 3:18 p.m. local time, public broadcaster NHK reported.

Three people have been injured, including one man who is unconscious, according to the report, Xinhua news agency reported.

According to the Sapporo Fire Department, witnesses reported hearing a "blast sound" and seeing flames from the windows. Footage from NHK cameras showed white smoke rising between buildings as firefighters worked to douse the flames.

Seventeen fire engines have been dispatched to extinguish the blaze.