Authorities in Phoenix, Arizona are searching for a missing 11-year-old patient whose life is at risk after her mother took her from the hospital before her leukemia treatment was finished.

Police say the little girl, who has only been identified as Emily, had her arm amputated because of an infection and a chest catheter inserted into her heart. Authorities are not sure why Emily's mother took her from Phoenix Children's Hospital on Wednesday night, but they are worried about the catheter still in her chest.

"Our concern right now is for that catheter to be medically removed. We understand that there is the possibility that the catheter could get an infection and thereby result in the death of this child really in the matter of days," Sgt. Steve Martos told KNXV TV station Thursday night.

Authorities said that the mother had removed an IV drip from the catheter, changed Emily's clothes and then walked the 11-year-old patient out of her ward at the hospital.

Surveillance cameras show that the mother and daughter then left the building before driving off in a black Ford van on around 10:30 p.m. local time Wednesday, according to a police press release.

Police are now searching for Emily and the mother, identified as Norma. They say a young boy was also seen leaving with the pair. Detectives have searched locally and outside for the girl and the mother.

Police say that it is imperative that anyone with information about the pair's whereabouts contact Phoenix police.

"We don't know why they left," Martos said, according to azcentral.com. "The primary concern of our detectives is the welfare of the 11-year-old victim."

The girl was scheduled to be released from the hospital Thursday morning. It is unclear how long the 11-year-old girl has been a patient at the hospital and authorities have yet to release the family's last name.