PHOENIX (AP) — Half an hour after putting her two children to bed, a Phoenix mother discovered they were gone. Frantic and fearful they had been kidnapped, she called police, who spotted her car near her apartment and tried to pull it over.

After it swerved and crashed into a pole, police discovered the driver was the woman’s 8-year-old son, and her 6-year-old daughter was a front-seat passenger.

The girl died Thursday of injuries suffered in the Wednesday night crash, while her brother suffered an ankle injury that didn’t appear serious, police said.

Police identified the girl as Aaliyah Felder. They said her seatbelt wasn’t fastened and the air bag in front of her didn’t deploy.

Police did not release the names of the 24-year-old mother or her son.

Sergeant Steve Martos said police did not know some details about what happened, including what prompted the children to go on the drive and how they got the car keys.

Police have not spoken to the boy at length so they don’t know why he was out driving the family car.

“There’s really no criminal element to any of it,” Martos said. “From mom’s standpoint, there’s nothing to indicate any neglect or abuse. From the kid’s point, he’s eight years old so his mental state is not culpable.”

After the crash, two patrol officers ran up to the crashed car, “thinking it’s a kidnap, that there’s a bad guy in there,” Martos said.

Instead, they found the children in their pyjamas and the girl seriously injured.

The crash occurred only a block from the apartment complex where the family lived, and the mother ran over after seeing the police activity.

She was visibly distraught after discovering the car and children belonged to her, according to Martos. “It was a horrible and tragic moment for her,” he said.

At the accident scene Thursday, someone had tied a pink balloon with “Princess” and two stuffed animals to a tree next to the wooden pole struck by the car, a 2010 Hyundai Elantra.

Scattered on the ground were parts of its bumper, the chrome “H” emblem from its grille, and medical packaging next to a pink shirt that appeared to have been cut off the girl by rescue workers.

Neighbour Elizabeth Marks wrote, “May she rest peacefully, God Bless,” and outlined a sunburst on a street-facing window screen using coloured chalk.

Marks said she knew the family only in passing and believed the little girl might have been deaf. The mother was friendly, she said.

“I’d always see her giving rides to the neighbours,” Marks said. “The whole family is nice.”

Martos said the mother had bathed the children and put them to bed at 9:30 pm, then went to bed herself at 10:00 pm, only to get up a short time later and find them missing, with the front door open and her car gone.

She knocked on doors in the neighbourhood and called police.

Just minutes earlier, police received at least two 911 calls from people who reported seeing the car being driven in the area.

One of the callers said the car had struck a fence before being driven off. Another caller said it appeared the car was being driven by a child.

Two responding patrol officers spotted the vehicle that crashed “almost instantly” after police turned on their emergency lights, Martos said. The police cars did not have their sirens on, he said.

From what police have pieced together, it appeared the children drove south about three miles from their home and then backtracked, Martos said.

Martos said there was no immediate indication that the officers did anything wrong.