She...Dawn Hochsprung (photo at link)...according to an “eye-witness account”.
http://www.newstimes.com/news/article/Principal-school-psychologist-ran-to-help-4119969.php
Thanks, not sure where I had heard the principal was a he...
From the Wall Street Journal article referenced in the newstimes.com (Connecticut) article that I linked above. . .
Without a lock to secure the door, a teacher at the meeting pressed her body against the door to hold it shut, Ms. Day said. That teacher was shot through the door in the leg and arm. “She was our hero,” Ms. Day said.
Carrie Usher, a fourth-grade teacher, said she believed the principal turned on the campus loudspeaker system, which broadcast sounds of “screaming and crying” through the school to warn others. Ms. Hochsprung and the school psychologist, identified as Mary Sherlach, were reported to be among the victims.