Waterford — A person brought a lone bullet to Waterford High School, prompting a short "shelter-in-place" Tuesday afternoon, but may have done so accidentally, police said.

Police said the bullet was found around 12:45 p.m. in a student support conference room. Video footage helped School Resource Officer Steven Whitehead pinpoint whom to interview.

The shelter in place was lifted about 1:45 p.m., Superintendent Tom Giard said Tuesday afternoon. Because police and school administrators quickly determined the source of the bullet and scope of the situation, the school had a normal dismissal and buses ran on schedule, Giard said.

He noted the district sent parents three notifications on the incident to keep them updated. Under a shelter-in-place, students participate in normal classroom activity but no one is allowed to enter or leave the school.

Police said they and school officials were continuing to investigate.