JENKS, Oklahoma - Police swarmed a quiet neighborhood in Jenks on Wednesday, investigating what they call a murder-suicide of a mother and her 3-year-old daughter.

Police said they did find detailed notes from 39-year-old Jaime Helms, and evidence that she may have tried to sedate the children before, they believe, she attempted carbon monoxide poisoning.

While Helms and her daughter died, her 5-year-old son somehow survived.

It was in the garage that Jenks police said the apparent murder suicide unfolded. Police Chief Cameron Arthur said that's where Helms and her daughter were found, and that it was the little girl's father, Helm's ex-husband, who found them in the white minivan with the engine running.

Neighbor, Andy Vivian said he tried to help, "He said he had tried resuscitation and I asked what I could do and he kinda pointed to the cab of his truck and said take care of the boy."

Police said they found the girl's 5-year-old brother alive inside the garage

"Found son in corner of the garage, in a corner. I was able to open the garage door and retrieve him successfully. He was sent to Saint Francis, so we hope he will be ok," Arthur said.

Vivian said he heard Steve Helms screaming around 4:30 in the afternoon, after police believe he arrived there to pick up the children.

"He was frantic, on the phone. I assumed talking to 911," Vivian said.

Police are now hoping to speak with the little boy and Helms's husband. They're looking for more information about what might have led to this apparent murder suicide.