NAPERVILLE, Ill. (AP) — A suburban Chicago woman ordered her 7-year-old son and a kindergartner she was babysitting to kneel on a bedroom floor and pray, then stabbed them both dozens of times as they begged for their lives, striking again and again as she told her son he was going to heaven, authorities said Thursday.

Officers who forced their way inside the locked apartment hours later found blood-spattered walls and the children's bodies in a master bedroom where moments before the killings they had been happily jumping on a bed, prosecutors said.

The Naperville police chief said it was the most gruesome sight he'd seen in three decades on the job.

Elzbieta Plackowska, a 40-year-old immigrant from Poland, offered numerous explanations for the violence, including that she was battling the devil and trying to rid the children of evil, DuPage County State's Attorney Robert Berlin said. But she eventually told investigators she stabbed the children and slashed their throats on Tuesday night because she was angry that her husband, a truck driver, was often away.