Chicago (CBS) — A deadly fire ripped through a three-story Portage Park apartment building Saturday, killing one and displacing dozens.

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Although investigators were at the scene throughout much of the day, the cause of the fire has not been determined.

Around 9 a.m., thick black smoke spread throughout the apartment building and so did calls to get out fast.

Seth McKonly escaped with a cut on his head that needed stitches.

“People were banging on the door, saying ‘hey, there’s a fire in the building,” McKonly said.

Firefighters tried for hours to knock down smoke and flames while a block away in a Red Cross warming van, shaken residents gathered for comfort.

Jazmin Guzman was making breakfast for her boyfriend and six-year-old daughter when she heard screams.

“You’re scared for your life and you don’t know how fast it’s going to go. You don’t know if the wind’s going to pull it over to where you are,” Guzman said. “It was the worst thing ever. In the moment, I was just thinking ‘get out’.”

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The fire did spread quickly.

Fire department officials said they had approximately 35 pieces of equipment and around 100 firefighters respond.

After the flames were extinguished, the van full of people counted their blessings but worried about their futures.

“I just started crying just because you don’t expect it to happen,” Guzman said. “You don’t think you’ll be that person.”

Some residents were being let back into the building Saturday evening.

Smoke detectors did work in the nearby apartments, but it is not known whether there were working smoke detectors in the apartment where the fire started.

The resident of the unit where the fire started was killed. The victim’s identity has not been released.

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The Red Cross wants to remind people to call them for help installing fire detectors that work for 10 years without changing batteries.