Chicago fire officials said three firefighters were seriously injured Thursday after a fire in a reported vacant building.

Firefighters were called to the two-story residential building in the 5400 block of South Justine Street in the Back of the Yards neighborhood around 11:30 a.m.

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"Companies reported to the scene. There was heavy fire on the second floor," Chicago Deputy Fire Chief Chris Serb told ABC7Chicago.com.

Four firefighters were injured and transported to the hospital.

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Fire officials said three were listed in critical condition but did not elaborate on what happened. The fourth firefighter was said to have non-life-threatening injuries.

"The challenge was the amount of fire, the heavy amount of fire, and just the weather. You know, it's still summertime, even though it's a little bit cooler than it was a couple weeks ago. We're still talking 80 degrees," said Serb. "There were no indications when they pulled up on the scene that this building was in fact vacant. It turned out that it was in fact vacant, but there were no indications."

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Neighbors told NBCChicago.com that they had called the city's non-emergency 3-1-1 hotline time and time again reporting the vacant building and asked for it to be demolished.

"The flames, I'm scared. I'm like I'm scared even for the firefighters because they're always putting their life under risk," neighbor Erika Echevarria told ABC7, adding that she saw firefighters working to contain the fire as she evacuated her nearby home.