Aliyah Kay Crowder was taken from Silver Hills Elementary School, 5770 W. 5100 South, at about noon, said West Valley City police Sgt. Mike Powell.
Aliyah's mother, 38-year-old Venus Athena Barker who does not have legal custody of the girl entered the school cafeteria at lunchtime, grabbed her daughter and started moving the girl out of the building, said Granite School District spokesman Ben Horsley.
When a school secretary asked Barker whether she had checked the girl out of school, Barker replied that she had, according to Horsley.
But the secretary insisted she had not.
Barker then handed over some purported legal documents, "which turned out to be nothing," Horsley said.
Horsley said Barker had a "stranglehold on the girl" as she proceeded to the parking lot.
The girl did not struggle, Horsley said, but "seemed quite shocked at the situation."
Powell called Barker's actions at the school "aggressive" and "very concerning."
The abduction happened around noon, but the Amber Alert was not issued until a few hours later as police worked to verify the information.
Powell said the girl's father, who has legal custody of Aliyah, is "obviously very concerned."
Barker is white, 5-foot-5, 150 pounds, with blue eyes and brown hair pulled into a ponytail. She is reportedly wearing a brown leather jacket. She may be driving a black or dark gray Chevrolet Malibu or Impala.
Aliyah is white, 4-foot-4, 70 pounds, with blue eyes, brown hair and a missing right upper tooth. She has double-pierced ears with hoops on one side and a skull post in the other.
She was last seen wearing a black coat with brown fur around the edges, a dark blue shirt, blue jeans and knee-high Converse boots, one with white laces the other with black laces. The jeans were tucked into the boots.
Barker's boyfriend, 34-year-old Sanford Grayson Barker, may be with her. He is known to carry a handgun, according to police.
Sanford Barker is described as 5-foot-10, 200 pounds with blue eyes and blond hair.
It is not known if the Barkers are married.
Aliyah was abducted by Venus Barker once before. In February 2011, she took the girl from Utah. The girl was found in October in Killdeer, N.D., staying in a trailer park with the Barkers, Killdeer police reported. She was reunited with her father.
Killdeer police found the girl after an officer attempted to stop Sanford Barker because of a broken tail light on his car, according to an October article in The Dickinson Press, a North Dakota newspaper serving Killdeer.
The article stated that Sanford Barker fled, leading police to the trailer park.
Anyone with information is urged to call police at 801-840-4000, or dial 911.