(CNN) -- An Irving, Texas, woman told a 911 operator that she strangled her two young children Monday because they were autistic, according to a recording of the call.
Saiqa Akhter, 30, has been charged with a single count of capital murder in the deaths of her 2-year-old daughter and 5-year-old son, police said.
Dallas County Police spokeswoman Jamille Bradfield said the single count covered a child under 5 and would probably be changed either to include multiple victims or to add a count.
"I'm just not sure which direction the police will go yet," she said.
A woman who identified herself as Akhter called police Monday evening and said she first tried to kill her children with bathroom cleaner, but they would not drink it. She told the 911 operator that she then strangled them with a wire and that they were on her bed.
Police and paramedics tried to resuscitate the children, but Zain Akhter died at the hospital Monday, and his younger sister, Faryaal Akhter, died at the hospital Tuesday evening, according to authorities.
On the tape, the woman tells the operator, "I killed them. I killed both of them. I killed my both kids. ... They are not doing anything. They are just blue. They are not taking any breaths. Their heart is not beating."
The operator asks her what happened.
"First, I tried to give them bathroom cleaner. I put in their mouth, but they don't drink it. I want them to drink it. They don't drink it. ... I grabbed their neck ... and they are no more," she says on the tape.
The operator continues to talk to the woman to keep her on the phone until officers arrive. She asks why she killed her children, and the woman says she wanted normal children.
"They are autistic. I don't want my kids to be autistic," she is heard saying in an even tone.
The operator then asks her what she is feeling, and she says "nothing."
Akhter is being held in the Dallas County jail in lieu of $1 million bail.
According to the Texas Department of Family and Protective Services, the Akhter family had a referral in 2009 for "neglectful supervision."
Spokeswoman Marissa Gonzales said the parents admitted leaving their son asleep at home while they rushed their daughter to the emergency room with respiratory problems. The boy was not harmed.
Gonzales said the parents expressed their understanding of the dangers of leaving a child so young home alone and were adamant that it would not happen again. They told Child Protective Services officials that they weren't thinking clearly because of their concern for their daughter.
Gonzales said the children were in good condition apart from the little girl's health issues and exhibited no signs of physical abuse. The home was clean and tidy.
Gonzales also said no one interviewed at the time had any concerns about the care of the children. Officials worked with family for more than two months, linking them with community resources that could provide support in dealing with the children's medical and developmental issues, she said.