Edmonton police are pleased the Amber Alert system worked as intended after an 8-year-old boy who was taken by his mother on Friday was found Saturday morning.

An alert went out just before 10 p.m. Friday night after the child was taken by his mother from an elementary school in southeast Edmonton earlier that day.

The boy was found unharmed near Okotoks — just south of Calgary — at about 5:30 a.m. Saturday. An off-duty Calgary police officer spotted the boy and his mother while driving. The mother was arrested by RCMP.

"We were able to safely recover this 8-year-old because of this system. So we're very happy to have it and I believe the majority of citizens are more than happy to assist us in those investigations," said Staff Sgt. Ashley Emerson at a media availability Saturday.

"It was a success."

Police said the boy was subject to a parenting order and the mother was not supposed to have custody on Friday.

As police searched for the pair they began to believe the situation was not simply a breach of a court order, but in fact an abduction.

"We were concerned for the well-being of the child and also of the suspect which led us to believe that the child was in danger," Emerson said.

When the boy left school Friday, he "wasn't picked up in a normal fashion and he was not taken with a jacket or his shoes."

There was also a marked change in communication with the suspect.

Edmonton police learned the mother and child switched vehicles as they headed towards Calgary, and the Amber Alert was updated to reflect the new information.

Emerson said police are grateful to the public who provided tips as well as the off-duty Calgary police officer who found the boy.

"We certainly appreciate the help he or she was able to provide us."