An Edinburg resident said a neighbor showed up to her front door on Sunday with her two children asking for sugar and milk.

That would be the last time she would see the family.

On Friday, the San Antonio Police Department announced the arrest of 34-year-old Marlene Vidal in connection with the deaths of her two children.

The children, believed to be ages 5 and 7, were found dead inside a burning vehicle in the 500 block of Richland Hills Drive between 5 a.m. and 6 a.m. 

Vidal was at the scene when police arrived, San Antonio Assistant Police Chief Jesus Salame Jr. said in a press conference.

Statements from Vidal, surveillance video and evidence gathered at the scene indicated Vidal is solely responsible for the death of the children, according to Salame. Investigators are working to validate the information Vidal provided and are in the process of interviewing family members and others connected to the case.

Vidal lived in Edinburg. A woman who lived in Vidal’s neighborhood provided Channel 5 News with surveillance video of Vidal and her two children showing them arriving at her home on Sunday. The neighbor said the family told her they were planning to move to Austin.

Another neighbor, Nohemi Jasso, said she would always see the woman with her children but never spoke with them.

“I’m sad for the children; people are supposed to keep them safe,” Jasso said.

While there is no clear motive for these killings, there are indicators that mental health may have played a role, and investigators are working to get a better understanding, according to Salame.

"What I will commit to you now is we're going to be working to find the truth, seek justice for these children, and support everyone affected by this tragedy," Salame said.

The investigation is active and ongoing.

Watch the video above for the full story.