Police on Sunday began a formal investigation of this weekend's fire at a senior housing complex in Jyväskylä, central Finland.
Chief Inspector Reima Rossi of the Central Finland Police Department told Yle that the probe has begun with technical studies of the cause of the blaze and interviews with eyewitnesses. These phases will continue through Monday at least. On Monday the Safety Investigation Authority (Otkes) is to announce whether it will also begin an investigation.
The key question is why and how the fire spread so quickly in the residential centre, which fire officials described as "baffling". The blaze began on Friday evening and was believed to be under control, but early Saturday spread to an adjoining building. A third block in the complex remained largely unscathed.
So far there is no indication that the fire was started intentionally. Officials suspect that it began on an upper-level balcony.
Rossi says the investigation will take months.
Almost 170 people, some of them in their 90s, were evacuated, initially to a nearby school. A few of them suffered from smoke inhalation, but there were no serious injuries.
The three blocks of flats, known as Palokan Ilona, were built in 2018 by SRV, which describes itself as the country's second-largest construction firm.
SRV Vice President Juha Toimela tells Yle that the firm has begun its own probe of the fire.
Military police and rescue services are patrolling the site to safeguard the technical investigation and private property.