ROSWELL, N.M. (AP) -- Students escaping chilly winter temperatures in southeastern New Mexico were congregated in the Berrendo Middle School gym, waiting for classes to start when they heard a loud pop.
Thirteen-year-olds Evan James and Kayla Koren, standing on opposite sides of the gym, said they looked up and saw blood and a fellow student on the floor, the victim of a gunshot wound to the face. A 12-year-old classmate holding a 20-gauge sawed-off shotgun stood nearby.
"I just saw blood everywhere," Essance Sosa, 12, said Tuesday. "Everyone started screaming and running."
Panic engulfed the gym and, eventually, the entire town as word spread by text and phone that a seventh-grade boy had opened fire, critically wounding an 11-year-old boy with shots to the face and neck, and hitting a 13-year-old girl in the arm.
The shooting was over in 10 seconds, police say, thanks to John Masterson, an eighth-grade social studies teacher. Authorities credit him with saving lives as he immediately stepped in and talked the boy into dropping his weapon. Masterson then held him until authorities arrived.
"He stood there and allowed the gun to be pointed right at him," Gov. Susana Martinez told a packed room of 1,500 or so people at a prayer vigil late Tuesday, "so there would be no more young kids hurt."
Officials also credit previous "active shooter" drills by Roswell Independent School District for preparing teachers and students, who say they were ready for what happened Tuesday morning.
"I thought it was a drill. I really did," Evan said. "Then, I realized it wasn't."
Investigators still aren't sure why the boy, who has not been named by authorities or formally charged, opened fire. Authorities said the boy sneaked the shotgun onto campus through a bag or musical instrument case.
State Police Chief Pete Kassetas disputed a report from a hospital spokesman who said nurses treating the boy indicated he was the shooter's target. He said a motive still is not known.
"We just don't have a lot of information," Kassetas told reporters late Tuesday.
The chief said police were combing social media and looking into reports some students may have been warned against coming to school.
The suspected shooter was transferred to an Albuquerque psychiatric hospital following a hearing Tuesday, according to attorney Robert Gorence, who is representing his family. Gorence said the family would release a statement Wednesday.
Kassetas said authorities have issued search warrants for the boy's locker, his bag and his parents' home. He said he did not know what had been found by late Tuesday. They're not yet sure where the boy got the gun.
Officials at University Medical Center in Lubbock, Texas, said an 11-year-old boy was flown there in critical condition and a 13-year-old girl arrived in serious condition.
The governor said late Tuesday that the boy underwent a second surgery. She identified the girl as Kendal Sanders, 13, and said her condition was upgraded to satisfactory.
Martinez said the family of the injured boy has asked that his name not be released while he recovers.
During the prayer vigil at the Roswell Convention Center hours after the shooting, an emotional crowd gathered to sing and hug as pastors spoke of healing and forgiveness. Pastors urged residents to pray for the suspected shooter.
"No superintendent ever wants to go through something like this," Roswell Superintendent Tom Burris said. "If you ever do, you want to have a strong community like here in Roswell," which is a center for ranching and farming and has a population of about 50,000.
Before the vigil, an emotional Martinez spoke to students who witnessed the shooting and urged them to talk to counselors and "let it out."
That's what she told Evan, who listened and nodded.
"We're all in shock," Kayla said. "I'm never going to forget what I saw."