DANVILLE, Ill. (AP) _ A baby sitter admitted feeding prescription medicine to four children, which killed the youngest and alarmed a community over what many feared was an exotic, unknown illness, police said Friday.

Christine Long, 25, was charged with involuntary manslaughter and child endangerment. She was jailed on $75,000 bail.

Long told police during questioning she was trying to discipline the children, said spokesman Larry Thomason.

``Ms. Long admitted to officers at that time that she had given an unprescribed medication to the children in an attempt to calm their behavior,'' said Thomason.

Authorities first suspected carbon monoxide poisoning, then an environmental illness after the four sons of Martin Cudney and Robin Quillen fell ill Monday. Some people were so frightened they heeded the advice of the fire chief and refused to stay in the apartment house they shared with the family.

On Friday, Long was accused of putting prescription medicine in the children's mouths, killing the couple's 9-month-old baby.

State's Attorney Mike Clary would not identify the drug or comment on a motive.

Long also was hospitalized this week, but authorities would not say whether she had taken the same medicine.

In announcing the arrest, Clary said authorities wanted to clear up the ``fear of the unknown'' the ordeal had created among the town's 33,000 residents.

During the investigation, authorities ruled out methane gas poisoning and viral infection, and sent tissue and food samples to the American Institute of Forensic Toxicology in Indianapolis for further tests.

``It approached almost a paranoid mania,'' said Vermilion County Coroner Lyle Irvin. ``It got to the point we were almost afraid to go to our homes and breathe the air.''

The baby, Cory Cudney, wasn't breathing when his parents returned from a night out. He and his brothers were being cared for by Long, a family friend.

Long was released from a hospital Wednesday, and the brothers _ Martin, 3, Cameron, 2, and 8-year-old half-brother Harley _ were released Thursday.

In an interview in Friday's Commercial News, Quillen said that when she arrived home, the children at first appeared asleep; Long was awake.

When the parents realized there was a problem, rescue workers were called, and one unsuccessfully tried to resuscitate Cory.

``Maybe if I didn't go to bingo that night, maybe he still might be alive now,'' Quillen said. ``Or maybe if I came home about 20 minutes sooner, maybe I could have done something to have saved my son.''