A 70-year-old man camping in a Walmart parking lot put a hot cook stove in his van, causing it to catch fire and spread to another van, burning two young sisters and killing one of them, authorities said Wednesday.

Prosecutors charged Roberto Lino Hipolito of Long Beach, California, with second-degree manslaughter and two counts of negligent fire, all felonies.

According to the complaint, Hipolito and his wife slept overnight in their van outside a Walmart in Fridley, Minnesota, a northern Minneapolis suburb. Surveillance video shows Hipolito cooking something on the stove, then putting it in the van before going into the store.

The van caught fire and spread to an adjacent van where police say two girls were alone up to an hour Tuesday morning as their mother shopped at the store.

Six-year-old Ty'rah White died Tuesday night while being treated at HCMC in Minneapolis, Anoka County Sheriff's Lt. Daniel Douglas

the Star Tribune. Her 9-year-old sister, Taraji White, remained in critical condition at HCMC on Wednesday evening, a hospital spokeswoman said.

The girls' mother, 33-year-old Essie McKenzie of Coon Rapids, Minnesota, said Ty'rah was "such a bright kid" with "a huge personality," and said her daughter "loved people."

"My baby fought a good fight. She was so strong through the whole process. She was even stronger than I was," McKenzie told

on Wednesday.

McKenzie told the station she let her daughters keep sleeping in the van while she ran into the store to grab something. The sheriff's office says McKenzie cooperated with law officers at the scene.

Fire investigators came to a preliminary conclusion that the fire started in the rear of Hipolito's Dodge Caravan and may have been caused by a cook stove recovered from the van, the complaint said.

When asked about the stove, Hipolito said he had not used it for several days, the complaint said. He later clarified that he had used the stove the previous night.

Video from just before the fire showed Hipolito placing the stove on the pavement by the rear of his van, then using the stove to cook something. After cooking, Hipolito put the stove in the rear of the van, which was driven to a parking spot closer to the store entrance, according to the complaint. Hipolito is seen going into the store, and about 2 minutes later his wife is told by passers-by that the rear of their van was on fire.

"She gets out and tries to remove belongings, but the fire intensifies within thirty seconds of the rear door being opened. Within 3-4 minutes the two vehicles on each side of the van are also on fire, including the one from which the children were ultimately recovered," the complaint said.

Investigators interviewed Roberto Hipolito again, and he said he had used the stove that morning to cook and then placed it in the rear of his van, according to the complaint. Before moving to the closer parking spot, he said he had tossed pillows and blankets to the rear of the van where the stove was.

Walmart is well known for allowing overnight RV parking at some locations, and the company's corporate website says it does so "as we are able," with permission coming from individual store managers. A frequently asked questions section on the company's website didn't cover other vehicles. A manager of the Fridley Walmart referred questions to a corporate media relations number, and messages weren't immediately returned.

Hipolito is scheduled to appear in court Thursday. The Anoka County Attorney's office says it does not know if he has an attorney who could speak for him.

A

page has been started to help the family of the victims.