Two 12-year-old Wisconsin girls arrested in the weekend stabbing of their friend plotted for months before the attack, the Waukesha Police Department said Monday.

The arrest of the girls, who are not identified because of their age, came just hours after they allegedly lured a young female, also 12, into a wooded area to "play a game" and attacked her, police say.

"One suspect held the victim down while the other suspect stabbed her 19 times in the arms, legs and torso," Waukesha Police Chief Russell Jack said at a Monday press conference.

The victim, despite having sustained several serious stab wounds to major organs, survived the attack and crawled out of the woods. A passing bicyclist spotted her and called 9-1-1, police said.

Jack said the two suspects, who were friends with the victim, planned the attack.

"Based on our investigation, it is believed that the suspects had planned to kill the victim for several months," he said.

A motive remains unclear, but Jack did say the suspects had an interest in a website "which was a collection of small stories about death and horror." That website has not been named.

The two suspects are being held on charges of attempted first-degree intentional homicide. They are expected to make their first court appearance Monday, at 2:30 p.m., Eastern time.

The victim remains hospitalized at Waukesha Memorial Hospital, where she is in stable condition.