A girl in sixth grade pulled a handgun from a backpack at her eastern Idaho school on Thursday and opened fire, hitting 2 fellow students and a member of school staff, officials reported, noting that she inflicted non-life-threatening injuries on them.

Jefferson County Sheriff Steve Anderson said the girl was disarmed by a teacher at Rigby Middle School in Rigby, Idaho, a remote community about 270 miles (435 km) east of Boise, and held until law enforcement arrived. Her name and exact age weren’t immediately disclosed.

“She fired multiple rounds inside of the school and out,” Anderson said at a news conference. “We don’t have a lot of details of why. That is being investigated.”

Parents of students were immediately called in to take their children home after the shootings, and classes will be canceled on Friday, Jefferson School District Superintendent Chad Martin said.

Martin added that “this is the worst nightmare any school district could ever face. We prepare for it and we’re never truly ready for it.”

Many law enforcement agencies are involved in the probe of the shooting, which took place shortly after 9 a.m. local time, according to Jefferson County Sheriff Anderson. Local media had previously reported that a male student was taken into custody following the shooting.

Depending on the findings of the probe, Jefferson County Prosecuting Attorney Mark Taylor said charges against the girl could include 3 counts of attempted murder.

Michael Lemon, trauma director at Eastern Idaho Regional Medical Center said none of the gunshot wounds were life-threatening. “They could be so much worse,” Lemon said. “We feel absolutely blessed.”