A high school student was arrested Tuesday after he donned a mask and fired a shotgun into a restroom ceiling, prompting a brief lockdown at the school, authorities said.

No one was injured when the shot was fired around 8 a.m.

Joshua Minks (search), 17, was charged with assault while on school property and unlawful use of a weapon, said prosecutor Wendy Wexler Horn (search). He was jailed on $250,000 bail.

Minks brought his father's 12-gauge shotgun to school in a duffel bag and assembled it in the boys' restroom, according to Police Chief Rick Baker (search) and court records.

When another student walked in and said the gun did not look real, Minks motioned for the student to get out of the restroom and then fired the weapon into the ceiling, officials said.

One other student who walked into the bathroom and ran out to notify school officials said the shooter had "a black cloth over his head with two eyeholes," according to a court document.

Farmington High Principal David Waters (search) and a teacher convinced the student to give up the gun and detained him until police arrived.

Baker said it was not clear exactly why the student, whom he described as mentally challenged, brought the gun to school.

"He said he did not intend to hurt himself or anyone else," Baker noted. But "he said he wanted to alienate himself from the school."