Three young children, including a 7-month-old boy, died in a horrific house fire as firefighters arrived to find the doors blocked late Wednesday in northwestern Indiana.

Fire crews fought back the 10:15 p.m. blaze in Hammond, about 25 miles south of Chicago, but the three victims had already perished inside, Deputy Fire Chief Kevin Margraf told NBC News.

The three victims were Jayden Young, 7 months, Alexia Young, 3, and Dasani Young, 4, the Lake County coroner’s office confirmed.

Fire officials said the children were unable to escape after the doors appeared barricaded by furniture. Investigators were unable to question the parents about why the exits were blocked.

The children's 28-year-old father and two other children, ages 5 and 7, survived the blaze. The father was in critical condition in the hospital after suffering third-degree burns, officials said. The children were given medical attention for smoke inhalation.

Fire officials said the survivors were huddled outside by the time the first crew arrived, the fire already consuming the front of the house. The blaze was put out in about two hours.

The 7-month-old baby was found just six feet from the front door, Margraf said. The older brother and sister were nearby in a final embrace.

They “were very close to one another,” Margraf said.

The children’s mother wasn’t home at the time.

Fire officials are investigating whether a space heater hooked up to a propane tank found inside the home may have sparked the blaze.