TRUSSVILLE, Ala. — A woman in Alabama was charged with animal cruelty after her dog died after it was left in a hot car for seven hours on July 4.

"Ultimately, I killed my dog," Stephanie Shae Thomas, 34, said at a press conference on Friday. "I can't change that. I want to, but I can't."

It was in the parking lot of a Trussville Walmart on Wednesday where concerned passersby spotted Sky, a 7-year-old rescue pitbull-boxer mix, alone in a car with the windows up on a very hot day.

Several people tried desperately to break the car window before police arrived.

"She was breathing very heavily and when you would tap on the door window, she would kind of move her eyes towards you," Stacy Guthrie, a witness who took cell phone video of the incident, told NBC affiliate WVTM.

When police arrived and finally broke the glass and got the dog out, she wasn't breathing. Some onlookers then helped put ice on the dog while Guthrie tried to resuscitate — but it was too late.

Thomas told WVTM in an interview Friday that she is a longtime drug addict with bipolar disorder, and she recently ran out of her medication.

Stephanie Shae Thomas of Trussville, Alabama, on July 5, 2018. Thomas, 34, was charged with felony animal cruelty. Jefferson County Sheriff's Department via AP

Just thinking about what she went through the last moment’s she was alive... She had to be waiting for me to come out there and help her," she said. "And I didn't."

Thomas said she didn't even remember driving to the Walmart store and only learned something was wrong after she checked out when a Walmart worker said, "The police are looking for you."

Store workers paged the woman over a public address system several times but there was no response, police told reporters. Parking lot surveillance footage showed Thomas arriving on the scene around 4 a.m. Wednesday morning.

Lt. Phil Dillon told news outlets Thomas went to the Trussville Police Department the day after and told officers she left the dog in her vehicle while she went inside to shop.

Thomas was released on $25,000 bond early Friday after spending a few hours in custody, Jefferson County jail records showed.

"I just don't understand, there are warnings out there and you think everyone knows not to leave their animals in the car but they still do," Guthrie told WVTM.