Updated 02/26/14 – 4:30 p.m.

OAK LAWN, Ill. (CBS) — Four people died of apparent gunshot wounds before a fire engulfed their home in Oak Lawn on Wednesday.

The final victim, a boy believed to be around five years old, was found late Wednesday afternoon. Officials said he had been shot.

The fire started around 5 a.m. at a 1 1/2-story home in the 9800 block of South 51st Avenue. When crews arrived, the house was nearly fully involved in flames.

Some of the closest hydrants were frozen, but firefighters were quickly able to tap into other hydrants.

Firefighters broke windows to get inside the home, where they discovered the bodies of two men. Both men were taken away in ambulances, and later pronounced dead.

As firefighters arrived at the scene they witnessed one of the men inside a car put a gun to his head and shoot himself. The second male had also suffered a gunshot wound.

After locating the two men, fire crews had to leave the home due to the raging fire and smoke.

On Wednesday afternoon crews found the body of a third person, a middle-aged woman, in the ruins of the home.

She was shot to death in the basement, officials said.

The roof and floor of the home collapsed into the basement during the blaze, and crews from several neighboring suburbs helped extinguish the fire, which was put out by about 9 a.m.

The South Suburban Major Crimes Task Force was assisting in the investigation.

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