As students saw that Halligan was armed, they ran, ducking into whatever classroom, office or closet was nearby, huddled in corners and hid behind furniture.
Principal Joseph Roy ran down corridors loud with the sound of teenage screams. "Lockdown!" he shouted.
During the next few minutes, Halligan moved through several second-floor hallways, stopping in front of the library, where many students were hiding under tables, some crying.
Then there was a "pop-pop-pop." Halligan fired three shots through his chin, one fatal, said Montgomery County District Attorney Bruce Castor.
While students stayed in their lockdown rooms, waiting for Roy and police to get them and take them to the nearby middle school, they sent text messages and read news of the shooting on the Internet. Later, a line of parents would lead away their shaken children.
*
Yesterday started out as a typical morning in Corey McCaslin's first-period Algebra III/Trigonometry class at 865-student Springfield High, students working on problems, a school coming to life.
Halligan walked into the class an hour late yesterday, unusual for the punctual junior. He was carrying a camouflage bag, about 2 1/2 feet long and a foot wide.
"He didn't seem flustered, angry, agitated," said Kyle Crathern, who was in Halligan's math class and who knew Halligan from Boy Scouts.
During class, students worked on math problems independently, and Crathern and Halligan talked about a movie they had seen. Halligan laughed about the poor report card he had gotten the day before but did not let on about the trouble it had gotten him in at home.
When Crathern questioned his friend about the unusually large bag, Halligan partially unzipped it to reveal a leather bomber jacket. Then he shut it again.
Opening the bag, "he was completely cool," Crathern recalled in an interview.
When the bell rang, about 9:10, Crathern stayed a few moments after to pack his things.
