DES PLAINES, Ill. (AP) — A mother and her four daughters were killed in a Wednesday fire that swept through their home in the Chicago suburb of Des Plaines, the city’s fire chief said.

Killed in the fire in the two-story apartment building were Renata Espinosa, 6; Genesis Espinosa, 5; Allizon Espinosa, 3; Grace Espinosa, 1; and their mother, Citahaly Zamiodo, 25, according to the Cook County medical examiner’s office and fire officials. The father of the children wasn’t at home at the time of the blaze.

“It is a sad day,” Des Plaines Fire Chief Daniel Anderson said at the scene. “This is a terrible day … a tragic day.”

Anderson and the state fire marshal, also at the scene of the blaze, did not give the cause of the fire.

Pabel Marrero, 52, a resident of the building, said he was in bed when he smelled smoke. A person knocking on his door told him he needed to get out because the building was on fire.

Marrero said police arrived at the scene quickly, but struggled to get to the upstairs apartment because the door leading to it was locked.

Anderson said heavy smoke was coming from the second floor when firefighters arrived. He said they immediately went into search-and-rescue and fire suppression mode.

“Unfortunately, during our attempts we located and recovered five victims,” Anderson said.

The children were pronounced dead at Advocate Lutheran General Hospital in Park Ridge, while the woman was pronounced dead at the scene.

The house, which had been divided into four apartments, according to village records, appeared to be severely damaged.

A firefighter hurt his knee battling the blaze and a police officer was cut by debris, city officials said.