Later, she tried to bury the bodies, but was unsuccessful in digging a hole large enough so she rolled them under a neighbor’s house, prosecutors said.

As she packed up her house and threw away items on Sunday, her acquaintance realized her admission was not a joke. She apparently showed him where the bodies could be found, prosecutors said, though it was unclear whether he actually saw the bodies under the house.

Using subterfuge, he drove around until he was able to flag down an officer. Police were dispatched to the scene where they found the children’s bodies. Thomas was charged with capital murder.

If convicted, she could face the death penalty. The decision whether to seek the death penalty is not typically made until months after an arrest.

On Sunday, Houston police descended on a row of modest houses, as neighbors gawked from behind police tape at the small yellow home of a young mother they barely knew. She was a relative newcomer to the Third Ward neighborhood — quiet, but friendly enough during strolls to a nearby park with her children.

“This is the type of stuff that you see on TV,” said Kita Thomas-Smith, the children’s aunt. “To actually feel it yourself is devastating. It’s hurtful. It’s ridiculous.

They were just innocent, growing kids.”

The case stirs horrific memories of another Houston mother, Andrea Yates, who confessed to drowning her five children in a bathtub more than 15 years ago. The killings sparked national discussion about postpartum depression and psychosis, and Yates’ 2002 conviction for the murders was overturned. Following a retrial she was found not guilty by reason of insanity, and is being treated at a state mental hospital in Kerrville.

Kita Thomas-Smith, whose brother married Sheborah shortly before the birth of the 7-year-old, said she had never seen the children’s mother exhibited signs of mental illness.

“There’s no reason you’d do this to your kids,” she said, adding Thomas could have taken them to a police station or to Child Protective Services if she didn’t want them.

Tejal Patel, a Houston spokesperson for Child Protective Services, confirmed the agency had previous involvement with the family, though she couldn’t provide details of the confidential case.

CPS has launched an investigation, and the Office of Child Safety will conduct “a top-to-bottom review of this case to see what led to this point,” Patel said, a process that could take months.

“Obviously we want to know how this happened, why this happened,” Patel said. “We just feel horrible. This is just a tragic case.”

The acquaintance alerted authorities about 10:15 a.m. He drove toward the Houston Police Department’s South Central patrol station at 2202 St. Emanuel, parking a block away to obscure the destination. At the station, he flagged down an officer and relayed what the woman had told him.

Patrol officers took the woman into custody and went straight to the house, where they discovered the bodies.

Smith said they are not aware of the woman having a history of mental illness. There had not been recent major calls-for-service to the house, which Thomas rented.

An autopsy will be conducted to determine the children’s cause of death.

Neighbors, gathering behind police tape surrounding the yellow house Thomas and her children lived in, were stunned by the news.

“I never would have thought she would do that. She didn’t seem like the type. She was always with a smile and friendly,” said Dee Davis, a neighbor. “How in the hell can she do something like this? You bring life into the world; it’s not up to you to take it out. I can’t get over this.”

George Shoupe, the landlord who owns the house Thomas rented and two adjacent houses, said Thomas and her family had moved into the house in April, so few of the neighbors knew them.

“I remember when they first moved in — the kids were happy and everything,” said Geovanna Brewer, a neighbor, who remembered Thomas’ friendly greeting in an encounter at a local convenience store. “It’s like a shocker to me.”

The mother has a minor criminal record, according to Harris County clerk filings. In July 2011, Thomas pleaded guilty to failing to identify herself to a peace officer, a misdemeanor for which she served a three-day jail sentence. She also pleaded guilty to two charges of misdemeanor theft in October 2010. She received probation for the same offense in August 2009.