Tragedy struck early morning on Tuesday after a 3-month-old baby was declared dead and three people, including two children, still missing after fire broke out at a three-story apartment building in the South Chicago neighborhood in U.S.

According to police as reported by Chicagotribune.com, the blaze started around 1:35 a.m. following reports to the police about someone setting a building on fire in the 8100 block of South Essex Avenue.

Witnesses on scene stated that they saw several people jump out of the building, which has about 32 apartments.

Lanita Smith, 25, who lives on the second floor of the building, said she woke up to loud sounds, which made her think someone was breaking into her apartment through the back door. When she got up, she saw that the back door of her kitchen is on fire. She said she opened the front door and saw smoke, but she was able to run out into the front yard.

The 3-month-old baby was said to have been taken in critical condition to Comer Children’s Hospital, where he or she later was pronounced dead at 2:40 a.m.

Also, a 48-year-old man was taken in critical condition to Advocate Christ Medical Center.

Two other people were taken to South Shore Hospital. One of them was in a fair condition, and the other was in a good condition, according to Chicago Fire Department media officials.

An adult and two children are still missing, according to officials.

As of 5 a.m., firefighters were still trying to access the part of the building where the fire started after dozing the three-story structure with water from ladders.

The cause of the fire is still being investigated, but according to a police source, people called the police about someone setting the building on fire right before the blaze broke out.