Updated 10/27/12 – 4:50 p.m.

CHICAGO (CBS) — Officials were investigating the cause of a fire that killed one man and injured his brother in the Logan Square neighborhood early Saturday.

CBS 2’s Courtney Gousman reports 43-year-old Jaime Martinez died after suffering smoke inhalation and second- and third-degree burns in a fire at a 2 ½ story frame residential building at 1645 N. Central Park Av. His brother was also injured in the fire.

The fire started around 1:30 a.m., according to the Fire Department. When crews arrived, they could see flames coming from the rear attic area.

Firefighters pulled Martinez’s brother out of the building, after spotting him hanging out of a first-floor window.

Fire Department Deputy District Chief Donald said the fire was extinguished within 20 minutes.

Once the fire was put out, a search was done, and that’s when the Martinez was discovered inside.

“They seen one fire victim hanging out of the first floor window. They threw a ground ladder and removed that person,” Hroma said. “They found one other victim inside the building and both victims were taken to [St. Mary and Elizabeth Medical Center].”

Martinez was pronounced dead at 2:05 a.m. at the hospital.

Roberto Hernandez tried to rescue Martinez from the attic, where he was found after the fire had been extinguished. Hernandez was left wondering if he could have saved Martinez if he’d had a few more seconds.

“It feels like just 10 seconds, you know? Ten seconds earlier, you know? Coulc have made a difference,” Hernandez said. “You think you can save somebody and all that. You know, you’re in the moment, you think you’re a hero. But when you get up there and that fire’s in your face, and that smoke is in your lungs – hard.”

Martinez and his brother, who is also in his 40s, were well-known to neighbors.

“They work hard all day, and then come home, drink a little beers, go to sleep,” Hernandez said.

Martinez’s brother was listed in fair condition Saturday morning. Firefighters said he had suffered smoke inhalation.

Approximately 12 people were living in the building and were searching for somewhere else to lay their heads after the fire left the building uninhabitable.

The cause of the fire remained under investigation Saturday morning, but family members said they believe an old electric heater sparked the fire. It had been turned on due to the cold temperatures overnight.

Watch & Listen LIVE