At least 24 people died after a fire broke out in a commercial building in Osaka on Friday morning, The Japan Times reported.

The blaze erupted in the city’s Kita ward and was reported to the fire department around 10.20 am local time. The blaze appeared to have erupted at a medical clinic located on the fourth floor of the eight-storey building. A cafe and a clothing shop were also located on the floor.

Authorities suspect that arson may have been the cause of the blaze. A report received by the police said that the fire originated from a liquid that came out of a paper bag that a man, apparently in his 60s was holding, according to The Japan Times.

Ryo Danno, the manager of an Italian restaurant across the street from the building, said that in the initial few minutes, he saw intense smoke billowing from the site of the fire. Danno said that he subsequently saw a woman being evacuated from the building.

Yumiko Inoue, a doctor at a hospital located nearby, said that many of the victims were employees or patients from the clinic, Reuters reported.

A doctor at a hospital where the injured persons are being treated said that many people appeared to have died after inhaling carbon monoxide, and said that they had limited external injuries, AP reported.

As many as 70 fire engines were brought in to bring the flames under control, the agency quoted officials as saying. The blaze was completely extinguished over six hours after it broke out.

Japanese Prime Minister Fumio Kishida offered condolences to the families of the victims and said that authorities were trying to identify the cause of the fire.