The 12-year-old gunman accused of wounding a teacher and two students when he opened fire at a New Mexico middle school planned his attack, police has said.
"We found evidence to believe it was thought out, and planned, prior," New Mexico State Police Chief Pete Kassetas told reporters.
In the latest school shooting to hit the United States, the boy allegedly burst into his school gym Tuesday, filled with 500 of his fellow students, pulled out a gun and started shooting.
The incident finished dramatically when a teacher, himself lightly wounded in the attack, talked the shooter into putting down the gun and surrendering to police.
Berrendo Middle School remained closed yesterday after the shooting, with residents organising a vigil to support the two injured students.
John Masterson, the teacher who stopped the shooter, sustained very minor injuries.
New Mexico Governor Susana Martinez said that one of the students, 13-year-old Kendal Sanders is now in "stable" condition as she recovers following surgery for a right-shoulder injury.
The other injured student, an 11-year-old boy whose name was not given "was injured more severely than Kendal," Martinez said.
The boy, whose age was initially identified as 12, was "in surgery for a second time (Tuesday) afternoon and his condition is still listed as critical," she added.
"He's suffered injuries to the side of his face and his neck."
Kassetas confirmed that the alleged shooter was 12 years old and used a 20-gauge shotgun he had hidden in a bag.
His motive remains unknown. But police were in the process of searching his locker at school, a bag and "a residence here in the Roswell area," without specifying whether it was the suspect's home.
The boy may also have warned his classmates of what was coming.
"We got some preliminary information that possibly some of the students were warned by the individual prior (to) the shooting not to go to school. We have not corroborated that yet," Kassetas said.
And asked about reports that the boy was bullied, Kassetas did not immediately deny them. "We're still working with that," he said.
