Police in Phoenix are searching for an 11-year-old girl who was removed from the hospital by her mother, where she was being treated for leukemia and still has a catheter in her chest.

Police said the little girl, who has been only been identified as Emily, also had her arm amputated due to an infection. The authorities are not sure why the mother removed the child from Phoenix Children's Hospital on Wednesday night, but are worried about the catheter still in Emily's 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 ABC News affiliate KNXV Thursday night.

Surveillance footage from the hospital shows the mother, identified as Norma in a police press release, leaving with Emily around 10:30 p.m. local time Wednesday. Police say Norma removed Emily's IV before walking her out of the hospital in street clothes.

A young boy was also seen leaving with Norma and Emily.

Police believe the family then left the hospital in a black van and have not been seen since. Detectives have made an effort to contact the family but to no avail, according to the statement.

It's not clear how long Emily had been a patient at the hospital. Police have not released the family's last name.