Candles used for light in an apartment without electricity probably caused a fire that killed six children inside, a fire department official said Monday as fire investigators continued sifting through debris.

The fire, the city's deadliest in years, has been classified as accidental but the Chicago Police Department also was investigating, which is a standard when there are deaths, Officer Marcel Bright said.

A preliminary investigation shows the Sunday morning blaze "was caused by candles" in the three-bedroom apartment on the city's North Side, Fire Cmdr. Will Knight said.

Knight said fire investigators have found no evidence of smoke detectors, although Chicago Alderman Joe Moore said Sunday that the landlord told him there were smoke detectors in the unit when the Ramirez family moved in.

The Cook County medical examiner's office identified the dead as Vanessa Ramirez, 14; Eric Ramirez, 12; Suzette Ramirez, 10; Idaly Ramirez, 6; Kevin Ramirez, 3; and Escarlet Ramos, 3. Friends said the Ramirez family had been baby-sitting Escarlet.

All six victims died of inhalation injuries and Vanessa Ramirez was burned, the medical examiner's office said Monday.

The Ramirez children's 40-year-old mother and a 3-month-old girl were treated and released from a hospital. Two other injured children were taken to area hospitals, but information on their conditions was unavailable Monday.

A friend of one of the Ramirez children said their mother originally was from Mexico, but the family had been in the United States for at least 16 years. A call to the Mexican Consulate in Chicago was not immediately returned on Monday.

Fire officials have said the family was relying on candles because they had been without power.

ComEd spokesman John Dewey has said the apartment had been without electricity since May but declined to say why it had been turned off, citing confidentiality issues.