NASHVILLE, May 19 (UPI) -- A Nashville high school graduate who allegedly was attempting a prank at her former school was foiled when she set off an alarm, police said.

Metro police Capt. David Imhof said the 17-year-old suspect was grabbed, but not bitten, by a police dog after officers arrived at Glencliff High School, The (Nashville) Tennessean reported Monday.

Police allege the suspect intended to throw water balloons at arriving students and faculty from her perch on the roof of the school.

Imhof said the teen was taken to Nashville General Hospital as a precaution. She faces trespassing and curfew violation charges, he said.