All four remain hospitalized, with Thron and Alexis Molina the most seriously injured, officials said.
Jouett is being held in a juvenile detention center. During a news conference Tuesday, District Attorney Andrea Reeb said she will seek to prosecute him as an adult.
In addition to the two murder charges, which carry a maximum sentence of life in prison, Jouett faces four counts of assault with intent to commit violent felonies, four counts of aggravated battery with deadly weapon, and one count of child abuse, officials said.
The authorities have not disclosed a motive, although Clovis Police Chief Douglas Ford confirmed reports that Jouett was suspended from school Friday for fighting with other students. As part of their investigation, police are trying to determine whether the teen told others he was planning the attack, Ford said.
It’s unclear how the shooter chose his victims.
On Monday night, witnesses described a chaotic scene as the shooter entered the library and began firing.
Lisa Baird told the Eastern New Mexico News that she observed a “young man” with a handgun fire several shots into the carpet in front of him, and yell: “Run! Why aren’t you running? I’m shooting at you! Run!”
Baird added she hid under a desk “and tried to squish up as small as possible,” but could hear the person continue shooting as he moved around the library.
“Then I heard his pants ‘shooshing’ as he approached the end of the reference desk,” Baird told the newspaper. “I heard a sound like a phone or something being put on the reference counter at the end of the desk, about four feet from my head.”
Sam Nathavong told KRQE News 13 that the shooter fired four or five rounds before approaching him.
“He just started unloading, pretty much the whole clip,” Nathavong told the news station. “I just kept my head down. I threw the table against the door to barricade myself in there. I thought he was coming my way but by then the cops got there.”
Ford said the gunman did not exchange fire with authorities and surrendered immediately when confronted. He did not resist arrest, the chief said.
Police then swept the building to ensure there were no other threats.
A photo posted to the Eastern New Mexico News website showed a man dressed in jeans and a short-sleeve black shirt being led away from the library in handcuffs.
It’s unclear how many patrons were inside the library when the shooting began, although it appears many were children.
One image from the scene showed a Clovis police officer, a rifle slung over his shoulder, carrying a small boy away from the building. Others showed children moving with police behind the relative safety of a parked van.
In another photo, a young woman, appearing dazed and bleeding, is seen being carried into an ambulance.
At a news conference Tuesday, New Mexico Gov. Susana Martinez (R) praised local police for their immediate response, singling out the chief, who, she said, was the first officer to enter the library to “make sure no one else would be killed.”
The FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives are supporting local authorities, officials said Tuesday.
Clovis, approximately 200 miles east of Albuquerque, is home to 40,000 residents and is near Cannon Air Force Base.
Police there have responded to shootings, but “not to this magnitude,” Clovis police spokesman Lt. Robert Telles told The Washington Post on Tuesday.
Clovis Mayor David Lansford called it “a senseless tragedy.”
“And there really isn’t a reason for it. I think, when it’s all said and done, you can come up with a lot of explanations, but I don’t think anyone will ever be able to put a reason on why these kinds of things happen.”
This story has been updated.