Dec. 8 (UPI) -- Authorities said Friday a high school shooting that killed two in New Mexico was orchestrated by a 21-year-old man who posed as a student to get inside the building.
Students Casey Jordan-Marquez and Francisco Fernandez were shot Thursday at Aztec High School, and more than a dozen others were injured.
Friday, San Juan County Sheriff Ken Christesen identified the gunman as 21-year-old William Atchison, who also died at the school.
Christesen said Atchison, a former student at Aztec High School, planned the attack and disguised himself as a student to get in. A search of his house found a paper with notes that read, "Work, packup, prep, walk, die," KOB-TV reported.
Authorities say Atchison lived with his parents and had worked at a gas station.
"It's important to understand how focused he was, how deranged he was, in his intent," Christesen said.
Police were called to the high school -- located about 180 miles northwest of Albuquerque -- at around 8 a.m. Thursday after reports of gunfire.
"We heard shots and it wasn't very close and then it stopped for a little bit," student Briley Dills said.
"Then we heard shots again and it was really close. And we were sitting in a corner up against a wall and I could like feel it vibrating ... and then it stopped."
Thursday, hundreds gathered for a candlelight vigil to remember the slain students.
Marquez's grandparents spoke at the vigil, and members of Fernandez's family wore shirts with his picture on it.
"She'd love to see everybody here," Marquez's grandfather said. "She loved everybody. If anybody was down, she was always there to cheer them up."
At the vigil, New Mexico Gov. Susana Martinez said she will dedicate resources to Aztec.
"As a family and as a community this shook us to our core but we have to remember that as a community we can heal," Martinez said.