An 11-year-old Utah boy brought a gun to school to protect himself from a Newtown-style attack, then showed the pistol to classmates during recess, according to reports.
He was detained on assault and weapons charges, a school spokesman said.
The boy, a sixth-grader, took the unloaded .22-caliber handgun to his school south of Salt Lake City in his backpack on Monday, the spokesman added.
Some ammunition was also found in the 11-year-old's backpack, but it did not appear to go with the gun, according the spokesman, Ben Horsley.
No one was injured in the incident, which occurred as jittery parents, teachers and students around the country faced their week at school since Friday's massacre.
Twenty children and six adult staffers at the Sandy Hook Elementary School in Newtown, Connecticut, were shot to death then by a lone gunman, Adam Lanza.
One 11-year-old Utah boy says he feared a similar attack.
The West Kearns Elementary student insisted he brought the gun to school to "protect himself and his friends from a Connecticut-style incident," Horsley said.
He is accused of waving the gun at three classmates during recess, however.
One of those students and a second classmate alerted their teacher, who "immediately took the student into custody and took him down to the principal's office," Horsley said.
After being briefly questioned, the boy (who has not been publicly identified) admitted bringing the gun to school, and the weapon was recovered minutes later.
Some parents questioned the decision not to initiate a security "lockdown," but school administrators reasoned that it made no sense to risk alarming students.
The boy was booked into a local juvenile detention center on one count of possession of a deadly weapon on school property and three counts of aggravated assault.
He was also suspended from school indefinitely.
Horsley described the boy's parents as shocked and cooperative; police found the gun belonged to a relative who has been living temporarily with the family.
He said the community was "rightfully" shaken by the incident.
"Because of the tragic shooting in Connecticut, people's emotions with respect to children's safety is right at the surface, and we're just as concerned as the parents."