Four buildings were damaged when a house fire spread in south suburban Blue Island, Illinois, early Monday morning. 

Blue Island fire officials said firefighters were called to the fire scene in the 2000 block of Vermont Street around 4:15 a.m. Police said the home was fully engulfed in flames when they arrived.

The fire quickly escalated to a two-alarm fire. Video from the scene showed heavy smoke billowing from the significantly damaged houses. The fire spread to three other homes and to a commercial business, Vanessa's Beauty Salon, at the back of one of the homes. 

"You just saw this orange fire in the sky and sparks, and it's just like, oh no!" neighbor Helen Omeish said.

It took about an hour for fire crews to bring the blaze under control. While the cause remains under investigation, the state fire marshal arson investigator was on the scene trying to determine if there perhaps was foul play. 

Fire officials said a firefighter was treated for heat exhaustion. The firefighter's condition is unknown at this time. 

A man who lives at that home where the fire started said he was at work when his neighbors called him to tell him his house was on fire. His brother, who suffered minor burns, was the only person home. He is now hospitalized to have his burns treated, his family said. 

The man also said there were four animals in the home at the time. They all escaped the fire but the family's black and brown German shepherd, Lexi, is missing. 

"I'm hoping someone in town finds it," Omeish said.

Another neighbor, whose home suffered roof and water damage, said he was awakened by firefighters entering his house with flashlights, telling him to get out as the fire began to spread. 

"I got up out of bed in shock. You know, like, what's going on. It was like a dream. Like a big boom, a big explosion just went off," Edward Castellana said.

Blue Island fire officials have not released details on the cause of the fire. 

• Chicago