A fire that forced dozens of people from their homes over the weekend started in the attic, the fire department says.

The investigation into a Saturday night blaze that forced more than 30 people to flee an apartment complex concluded the fire broke out in an electrical box above the furnace room. However, the fire department says it wasn’t caused by an electrical issue.

Fire Marshall Randy Ryba said on Thursday that the fire was likely caused by heat produced from an electrical conductor that wasn’t installed properly.

The Red Cross assisted the families immediately following the blaze, providing people with food, clothing and shelter.

Fire officials say it might be months before people will be able to return home due to extensive fire damage.