(CNN) How, how, how? The question weighs on investigators as they work to determine what led to a Chicago house fire that killed 10 apparently unaccompanied children who had gathered for a slumber party at a West Side home.

Illinois authorities are investigating allegations of neglect, officials said Tuesday, but provided little additional detail -- adding to a litany of questions about what started the fire and why the children weren't able to get out.

The bodies of eight children, ages 3 months to 16 years, were discovered Sunday after firefighters put out the fire. Two more victims, both 14, later died at John H. Stroger Jr. Hospital, said Natalia Derevyanny, a Cook County Bureau of Administration spokeswoman.

Amber Ayala mourns the loss of 10 kids killed in a Chicago house fire Sunday.

Though Chicago Fire spokesman Larry Langford initially said no smoke detectors were found inside the home, the department's news affair office said Wednesday that investigators found a smoke alarm, but it did not have a working battery.

While landlords must supply smoke alarms, the department's Office of Fire Investigations said, tenants are charged with maintaining them.

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