? The non-fatal stabbing of a Hendrick Hudson High School student overnight drove the school to beef up security Thursday.

The teen wasn?t seriously injured in the off-campus attack Wednesday night, but nonetheless, the high school and Frank Lindsey Elementary School were both placed on lockout, with students allowed to enter and exit only through the main doors.

Some students say they weren?t told about the stabbing but did notice increased security. In an effort to ease worries, the principal announced that the lockout and the tragic Sept. 11 anniversary were unrelated.

Police are investigating the stabbing.