Police believe an explosion at a Sapporo building that left 42 people injured on Sunday was caused by gas leaking from more than 100 deodorizer spray cans, intended for disposal, at a real estate agency.

The wooden building, which housed the agency along with a Japanese-style pub and an adjacent clinic, collapsed in the blast, local authorities said.

The explosion occurred at around 8:30 p.m. in Toyohira Ward, resulting in a fire that was extinguished at 2:10 a.m. An employee of the real estate agency told police about the disposal of the spray cans. It is suspected that gas from the cans ignited when a water heater was switched on.