Fire crews extinguish a fire after heavy flames damaged the second floor of a townhome in the 2100 Block of Sassafras Way in Wonder Lake Wednesday afternoon. | Photo: Tracy Mathesius

Residents were displaced after a fire started in a townhome in Wonder Lake and sent flames billowing out the windows Wednesday afternoon, fire officials said.

The McHenry Township Fire Protection District responded around 12 p.m. Wednesday to the 2100 Block of Sassafras Way in Wonder Lake for a report of a structure fire.

McHenry Township Fire Protection District Battalion Chief Kevin Sears said fire crews arrived on the scene within five minutes.

They found flames coming from the upper floor windows of an occupied three-story, multi-family structure.

Fire crews extinguish a fire after heavy flames damaged the second floor of a townhome in the 2100 Block of Sassafras Way in Wonder Lake Wednesday afternoon. | Photo: Tracy Mathesius

Sears said firefighters initiated an aggressive interior fire attack while searching for occupants within the residence.

Additional firefighters cut a hole in the roof to ventilate heat and smoke from the unit and prevent the spread of fire into other parts of the building.

The occupants were home at the time of the fire and escaped without injury before the fire department arrived, Sears said.

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Smoke detectors were present in the unit and operational. There were no firefighter or resident injuries.

Fire crews extinguish a fire after heavy flames damaged the second floor of a townhome in the 2100 Block of Sassafras Way in Wonder Lake Wednesday afternoon. | Photo: Tracy Mathesius

The McHenry Township Fire Protection District was assisted by the Richmond and Wonder Lake fire districts.

Additional fire departments staffed McHenry fire stations and responded to several other emergencies while crews were battling the fire.

The cause of the fire has not been determined yet, Sears said. The townhome was deemed uninhabitable.

The fire remains under investigation by McHenry Township Fire Protection District investigators.