Updated 09/08/14 – 2:55 p.m.

CHICAGO (CBS) — Four children were killed and two adults were seriously injured in an apartment fire early Monday in the Roseland neighborhood.

CBS 2’s Mike Puccinelli reports the first 911 call came in shortly before 3:30 a.m. in the 11200 block of South Vernon Avenue.

“The companies were here in approximately three minutes. Upon arrival, we had heavy fire blowing out the second and third floor windows of this building, and two adults were on the ground. They apparently had jumped from the third floor window,” Assistant Deputy Fire Commissioner Michael Fox said.

Firefighters said the blaze started on the second floor, and quickly spread to the third-floor apartment where the children died. The fire started from an open flame, possibly from a candle, lighter or cigarette, according to Fire Department spokesman Larry Langford.

Relatives have identified the children as 16-year-old Carliysia Clark, a sophomore at Wendell Phillips Academy High School; 13-year-old Carlvon Clark and 12-year-old Shamarion Coleman, who both attended Ida B. Wells Preparatory Elementary Academy; and 7-year-old Eri’ana Patton Smith, who attended Pullman Elementary School.

Firefighters said Carliysia died huddled inside a closet, trying to use her body to shield a younger sibling from the flames.

Eriana Smith, Carlvon Clark, Shamarion Clark, and Carliysia Clark (left to right) were killed in a fire at their Roseland apartment early Monday. (Family photos)

Eriana Smith, Carlvon Clark, Shamarion Clark, and Carliysia Clark (left to right) were killed in a fire at their Roseland apartment early Monday. (Family photos)

The children’s mother, Shamaya Coleman, broke several bones jumping from the window. She was initially listed in serious condition Monday morning at Advocate Christ Medical Center in Oak Lawn and has been upgraded to good condition. Her boyfriend, Nate Johnson, initially was taken to Christ, but later was tranferred to the burn unit at Loyola University Medical Center in Maywood. Johnson initially was in critical condition and remains critical as of Monday afternoon.

Witnesses said Coleman and Johnson were screaming for help before they leapt from the window.

“They jumped before the fire department got here, but the fire department did get here immediately. Once they got here, I informed them that there were children in that apartment, but by the time they got here, the whole apartment was already in flames,” neighbor Darlene Jones said.

Shamaya Coleman (right) and her boyfriend Nate Johnson (left) jumped from the window of Coleman's third-floor apartment after a fire started early Monday. Coleman's four children died in the blaze. (Photo supplied to CBS 2)

Shamaya Coleman (right) and her boyfriend Nate Johnson (left) jumped from the window of Coleman’s third-floor apartment after a fire started early Monday. Coleman’s four children died in the blaze. (Photo supplied to CBS 2)

Langford told WBBM Newsradio’s Bernie Tafoya an initial investigation by the Office of Fire Investigations determined the fire likely turned fatal because the front door to the third-floor apartment had been left open, allowing the fire to to spread into the living room from the hallway.

Langford said fire investigators were told the children woke up the adults after discovering the fire, but were unable to get out, because the fire blocked their escape.

“For some reason, the front door was left open. Flames came into the living room area, and once the living room ignited, it cut off the escape through the back door, leaving the occupants with no way to get out except the windows,” he said.

Langford also said investigators found no working smoke detectors in the second-floor unit where the fire started, or the third-floor unit where the children died, although there was a working smoke detector in the building’s common area.

Buildings Department records show the building was cited as recently as June for missing smoke and carbon monoxide detectors. The building has been cited at least nine times in the past 10 years for various code violations, including missing smoke detectors, collapsing ceilings, problems with the exterior façade, and more.

A Buildings Department spokeswoman said inspectors were at the building Monday morning to evaluate the condition of the building.

She said the building has been in court several times since 2006 for various code violations, including nearly 40 alleged violations this year alone.

“The Department of Buildings had numerous contacts with this property during 2014. The most recent contact was June 9, 2014 at 11242 S. Vernon, where a total of 17 violations were cited and processed for Circuit Court. These violations included missing smoke detectors in various locations at the 11240 and 11242 S. Vernon buildings and missing carbon monoxide detectors at the 11242 S. Vernon building,” spokeswoman Mimi Simon said in an email. “The Department of Buildings also responded to a heat complaint on March 14, 2014 that led to 21 violations.”

The March code violations were being processed by the city’s Department of Administrative Hearings, and the next date in the case was scheduled for next month.

Although two neighbors said the back door to the third-floor apartment was broken, a Fire Department spokesman said investigators determined the residents could have used it to escape if they could have reached it, but the fire blocked their path to the back door.

“We didn’t see anything to keep them from getting out the back door, if they could have made it to the back door; but because the living room was involved in fire, they could not,” Langford said. “They couldn’t get out the back door, because they couldn’t get to the back door. They would have had to go through the burning living room to get to the back, and they couldn’t do that, so the condition of the back door had no bearing – from what we can see – on their escape. They couldn’t get to it.”

CBS 2’s Susanna Song reports, when the children’s father found out about their deaths while visiting their mother at the hospital, he fell to his knees and sobbed. The three oldest kids were his biological children. He helped raise the youngest.

The children’s aunt said he was planning to pick them up last night to stay at his home. He grieved and mourned openly outside the hospital.

A couple dozen family members arrived at the hospital to comfort each other, crying on each other’s shoulders.

“My nieces and nephews gone now; they was great kids, and they will be missed,” their uncle, Calvin Clark said. “We’re going to get through this, but they’re gone now.”

Calvin Clark said his oldest niece, Carliysia, was ranked number 3 in her class at Phillips.

“All A and B student. Carlvon, he was in 8th grade. He was getting ready to graduate. He was on his way to the military. My brother, Justin, signed him up to go to the military school. Shamarion, he just loved to dance, and the other little baby, she was just a sweetheart,” he said.

Their aunt, Monica Coleman, asked for prayers for her sister.

“Pray for my family. You know, my sister has lost four of her children, and we just need prayers. That’s just basically it,” she said. “She’s fine. She has quite a few injuries, but she’s going to make it.”

The principal at Wells described Carlvon and Shamarion as well-behaved children. Their father is the school’s wrestling coach. The principal said crisis counselors were being made available to students.

Firefighters said the residents of all other units in the building were able to escape unhurt.

The American Red Cross said at least 36 people lived in the building.

The cause of the fire was under investigation, but firefighters did not believe it was intentionally set.