A Phoenix high-school student says she posted a Columbine-like threat online because she was "frustrated."

Now, she's under arrest.

Phoenix police booked the 16-year-old Bostrom High School student.

Someone alerted them after reading the message on the girl's MySpace page. It apparently said she wanted to kill her classmates.

Nothing suspicious was found at the girl's house. However, the girl could face even more charges if anything else turns up.