Firefighters work to extinguish a massive fire at an apartment complex in the 500 block of Devonshire Lane in Crystal Lake early Wednesday morning | Photo by Alex Vucha.

Fire officials said that the massive three-alarm fire at a Crystal Lake apartment building early Wednesday morning was caused by an unattended candle and damage is estimated at $3.5 million.

The Crystal Lake Fire Rescue Department responded at 3:02 a.m. Wednesday to a report of a structure fire in the 500 block of Devonshire Lane.

Six minutes later the first fire crew arrived and found a two-story multi-family apartment style building with flames coming from the roof, Crystal Lake Fire Rescue Chief Paul DeRaedt said.

“Police and fire personnel immediately began to evacuate the residents while other crews worked to put water on the fire,” DeRaedt said. There were no injuries to any of the residents but one firefighter suffered minor injuries.

A third alarm was requested through the Mutual Aid Box Alarm System (MABAS). The fire was first noticed on the roof and quickly spread the entire length of the building through the attic, DeRaedt said.

[Suggested Article]  2 arrested after allegedly being found with large amounts of fentanyl, cocaine at motel in Crystal Lake

Fire crews set up multiple ladder trucks to get water onto the roof and attic. Firefighters also helped two residents evacuate their apartments by ladder. 19 apartment units in the building were deemed uninhabitable due to fire and water damage and 21 residents were displaced.

Some pets were rescued by fire crews and reunited with their owners, Crystal Lake Deputy Fire Rescue Chief Christopher Olsen said.

The fire was declared under control at 5:20 a.m., three hours after it started. The American Red Cross and building management are working with the displaced residents to provide shelter.

Olsen said that investigators believe an unattended candle on a balcony may have caused the fire, which was deemed accidental in nature. Damage was estimated at $3.5 million.