Meanwhile, art teacher Patti Nielson was inside the school; she had noticed the commotion and walked toward the west entrance with student Brian Anderson. Nielson had intended to walk outside to tell the two students, "Knock it off," thinking they were either filming a video or pulling a student prank. As Anderson opened the first set of double doors, the gunmen shot out the windows, injuring him with flying glass; Nielson was hit in the shoulder with shrapnel. Anderson and Nielson ran back down the hall into the library, and Nielson alerted the students inside to the danger, telling them to get under desks and keep silent. She dialed 9-1-1 and hid under the library's administrative counter. Anderson fell to the floor, bleeding from his injuries, then hid inside the magazine room adjacent to the library.