An explosion on Tuesday afternoon in a building in Sapporo’s Susukino entertainment district that has left four people injured — with one man reportedly unconscious — is suspected of being caused by arson, Hokkaido police sources said Wednesday.

The police are conducting an on-site investigation, believing that the unconscious man in his 40s, who was taken to hospital in critical condition, might have started the fire.

According to police, the incident occurred at around 3:20 p.m. in a girls’ bar on the second floor of a six-story building in a densely packed area of Susukino, lined with multitenant buildings.

An emergency call reported “an explosion and flames visible from a window,” NHK reported, citing the Sapporo Fire Department.

Seventeen fire trucks were dispatched to the scene. Footage from local broadcaster HBC showed white smoke billowing between buildings as firefighters sprayed water onto the flames. Approximately 70 square meters spanning the second and third floors were consumed by the fire.

Aside from the seriously injured man, three others, two men in their 30s and 50s and a woman in her 20s, all sustained burns but are not in life-threatening condition.

Police suspect arson may be the cause of the blaze as several people told them that a man spread a gasoline-like liquid in the bar and set it on fire. Police plan to question the three hospitalized victims when they recover to determine the circumstances leading to the fire.

[bio]Information from Jiji added[bio]