BAILEY, Colo. — He wore a hooded sweat shirt and carried a camouflage backpack. Some students saw him but no one knew the man walking through the close-knit high school on Wednesday.
He entered a classroom, fired a gun and lined the frightened students up against the blackboard, 16-year-old Cassidy Grigg told his father.
"He hand-picked the ones he wanted to get out," Tom Grigg said, recounting his son's description. He told six girls to stay.
More than four hours later, authorities said, one of the girls was dead and the gunman took his own life as a SWAT team moved in. Another girl escaped unharmed; four others had been released earlier.
Authorities said they did not know who the gunman was or what triggered the standoff with deputies at the 460-student Platte Canyon High School, nestled in the mountains about 35 miles southwest of Denver and a short drive from Columbine, the site of one of the nation's deadliest school shootings.
"I don't know why he wanted to do this," a shaken Park County Sheriff Fred Wegener said after the standoff ended.
Classrooms were locked down and deputies rushed to the scene after the school intercom announced "code white." The gunman was cornered in a second-floor classroom with his hostages, authorities said, while other students were shepherded to safety from the high school and the adjacent Fitzsimmons Middle School.
The sheriff said the gunman threatened the girls throughout the ordeal, and authorities decided to enter the school after the man cut off negotiations and set a deadline.
"It was then decided that a tactical solution needed to be done in an effort to save the two hostages," Wegener said, his voice breaking.
He said authorities used explosives as they entered the classroom, only to have the man fire at officers, shoot one of the girls and then himself.
A spokeswoman at St. Anthony's Hospital in Denver said the girl was declared dead upon arrival.
Acquaintances and a co-worker of the girl identified her as 16-year-old Emily Keyes.
Keyes was a member of the volleyball and debate teams and was getting involved with cheerleading, said senior Desaray Trujillo, 17, who had known her since the second grade. Keyes also worked as a waitress at a restaurant in town.
"I'm feeling a lot of things right now, I'm feeling rage, I'm mourning," said her boss, Chip Thomas. "She was a good kid, she'll be missed."
Asked later whether he thought he had made the right decision, Wegener said, "Yes."
"I have to go and eventually I have to face a family about the fact that their daughter is dead. So, what would you do?" said Wegener, whose own son is a student at the school.
Students described a chaotic scene inside. Ani-Rae Lovell said everyone was told to stay in their classrooms.
"It took about 25 minutes before someone opened the door, we didn't know who it was," she said. "It was a Park County sheriff."
Students from both the high school and middle school were taken by bus to another school for a head count, and there were cheers from parents as their loved ones arrived.
Cassidy Grigg told his father the gunman had ordered him to leave the classroom but he resisted, saying he wanted to remain with the girls who had been told to stay behind.
"The guy flipped him around and put the gun in his face and said, 'It would be in your best interest to leave,"' Grigg said.
The lines of students fleeing the schools and the frantic parents scrambling to find their loved ones reminded many of the scene at Columbine High School in 1999, where two students killed 13 people before taking their own lives. The suburban Denver high school is less than an hour's drive from Bailey.
Sherry Husen, whose son plays on the high school football team, said her family moved to Bailey, a town of about 5,500 people, about 14 years ago. It has become largely a bedroom community for commuters who work in Denver.
"We moved up here for the mountain solitude, and I just never thought this would happen in this school, but it happens everywhere," Husen said.