NEWPORT -- Students and faculty of Nokomis Regional High School spent nearly two hours hunkered inside classrooms Tuesday morning after an apparently errant toss of a ball bearing left a bullet-sized hole in a window that police and administrators originally believed was the result of a gun shot.

The bearing shattered a pane of safety glass in an exterior doorway, causing a loud snap and sending the school into lockdown mode. Students and teachers spent the next two hours locked inside classrooms as police and school administrators investigated.

"The window looks exactly like a rifle (bullet) went through," said Leonard R. MacDaid, chief of the Newport Police Department. "You'd have a hard time telling the difference."

Students were entering the building and settling into their home rooms a little before 8 a.m. when three male students were apparently tossing the metal ball that sailed away and broke a window near where faculty and students were gathered inside the building, said MacDaid.

"We've found out now it was just thrown,"he said. "It looks like students fooling around."

MacDaid did not know the ages or hometowns of the students believed responsible for the incident.

MacDaid was unsure if the ongoing investigation would lead to charges.

Newport police officer Kevin Wintle, the school's resource officer, was standing near the window when the ball struck.

Wintle heard the loud noise and saw the small hole in the center of the shattered window, said Arnold Shorey, the school's principal.

"The investigation is still pending, and the person responsible has come forward," Shorey said. "By all accounts, it appears to be an accident, but it was not reported in a timely fashion.

"The lesson learned is, when mistakes are made, come forward immediately," Shorey said.

Students returned to classes at around 9:50 a.m., the principal said.

The atmosphere inside the school remained calm throughout the ordeal, Shorey said.