HOUSTON, Texas (CNN) -- A 36-year-old mother was charged with capital murder Wednesday in the deaths of her five children police said they believe were drowned in a bathtub of their home.

Houston police spokesman Robert Hurst said Andrea Yates was charged with five counts of capital murder. The children ranged in age from 6 months to 7 years. Each count carries the death penalty if she is convicted.

Yates was being held in a Houston-area women's detention facility, Hurst said.

Police spokesman John Cannon said Yates has suffered from postpartum depression, a condition that affects some mothers typically up to a year after childbirth. Cannon said Yates had experienced postpartum after the fourth child.

"The suspect has been treated for postpartum depression for the past two years," Cannon said.

Hurst refused to discuss Yates' mental state. "I would say she's answering the questions of the homicide investigators, and her demeanor right now, according to the investigators, is that she's talking to them," Hurst told reporters at news conference late Wednesday.

Officers went to the Yates home southeast of Houston after getting a call from the woman shortly before 10 a.m.

"The responding patrol officer came to the door and the woman who was still breathing rather heavily at that time said, 'I just killed my children,'" Cannon said.
Yates led the police to a bedroom where a 6-month-old girl and three boys ages 2 to 5 were found dead with a sheet over them on the bed, authorities said.

Cannon said Yates "didn't tell us about the fifth body" -- a 7-year-old boy, the oldest of the siblings, who was found by an officer in the bathtub.

Hurst said the children's father, Russell Yates, was at work and returned to the home after being notified by authorities. He is a computer engineer who works with the space shuttle program at Johnson Space Center.