An explosion Tuesday afternoon in a building in Sapporo’s Susukino entertainment district has left at least three people injured — with one man reportedly unconscious — according to media reports.

The incident occurred at around 3:18 p.m. 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.

The fire department confirmed that the injured include a man who remains unconscious and two others, a man and a woman, who sustained burns, NHK said.

Police and fire officials are working to determine the cause of the blaze.