A western Pennsylvania woman heard "crazy voices" telling her to push her sons underwater before she sat on the boys in the bathtub, drowning her 3-year-old son and leaving his 6-year-old brother in critical condition, police said in a criminal complaint.

Laurel Michelle Schlemmer, 40, of McCandless, was jailed without bond after she was arraigned early Wednesday on charges including criminal homicide, aggravated assault and child endangerment.

Schlemmer told Allegheny County detectives she tried to drown her two youngest sons, 6-year-old Daniel and 3-year-old Luke, after her 7-year-old son, whose name was not listed in the complaint, left for school Tuesday morning.

She put the older boy on his school bus at about 8:40 a.m., then told the younger boys to take off their pajamas and get into the bathtub.

"Schlemmer said after the boys got into the tub she got into the tub 'fully clothed' and 'crazy voices' were telling her to push the boys down into the water," the complaint said. "Schlemmer explained that at one point she (was) sitting on top of boys while they were under the water in the tub."

The detectives said Schlemmer went on to explain she "thought she could be a better mother" to the oldest boy "if the other two boys weren't around and they would be better off in heaven."

Schlemmer pulled both boys out of the tub and laid them on the bathroom floor while she called 911. She told police she never attempted CPR because she did not know how to do it.

Word that the two little boys were found unresponsive stunned neighbors in the quiet, upscale bedroom community a few miles north of Pittsburgh. They described the family as religious and said Schlemmer was a stay-at-home mom whose husband, Mark, was working at the time.

Nobody returned a message left on the home's voicemail early Wednesday. The greeting featured a female voice telling callers to have a "blessed day."

Court records don't list an attorney for Schlemmer, who faces a preliminary hearing April 11, but indicate this wasn't the first time she encountered police regarding the treatment of her children.

She received a citation for leaving a toddler unattended in a parked car on Sept. 5, 2009, in nearby Ross Township. Court records don't indicate which child was in the car, but police said the car's interior was 112 degrees when officers arrived. The child wasn't injured and Schlemmer paid a small fine, according to court papers.

On Tuesday, emergency crews took Luke and Daniel Schlemmer to UPMC Passavant Hospital, where the younger boy was pronounced dead at about 10:50 a.m. The older boy was transferred to the pediatric intensive care unit at Children's Hospital of Pittsburgh at UPMC, where police said he remained in critical condition.

Schlemmer was jailed without bond because in Pennsylvania bail is not granted to people charged with criminal homicide, except in rare circumstances.

Police also charged Schlemmer with attempted homicide, reckless endangerment and tampering with physical evidence, for allegedly hiding her wet clothes in a trash bag and then hiding that bag under three other bags.