MISSOULA, Mont. - The Latest on authorities finding ammunition in a Missoula school (all times local):

5:10 p.m.

Montana officials say they have determined there is no active threat after a loaded magazine of ammunition was found in a high school hallway.

Missoula County Public Schools spokeswoman Hatton Littman said in a statement Monday that Sentinel High School staff and police searched the building after students were sent home.

The statement says school will resume on Tuesday. Counseling services will be offered to students and staff.

Missoula Police Sgt. Travis Welsh says a construction worker found the ammunition magazine Monday morning and turned it in to school officials.

They immediately imposed a lockdown, which prevents anyone from entering or leaving the school and keeps students in their classrooms.

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1:15 p.m.

Officials in a Montana high school have dismissed students early to conduct a thorough search of the school after a magazine of ammunition was found in a hallway.

Authorities say a handgun was not found in an initial search of Sentinel High School in Missoula on Monday.

Missoula Police Sgt. Travis Welsh says a construction worker found the ammunition magazine Monday morning and turned it in to school officials.

They immediately imposed a lockdown, which prevents anyone from entering or leaving the school and keeps students in their classrooms.

School officials said in an email to parents that dismissing students after noon would allow for a more comprehensive search and would be the safest solution for the school.

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11:05 a.m.

A Montana high school has been placed in lockdown after a loaded, handgun ammunition clip was found in a school hallway.

Police and officials at the Sentinel High School in Missoula were investigating Monday where the clip came from and whether a firearm was in the school.

Missoula Police Sgt. Travis Welsh says no firearm was immediately found.

Welsh says a construction worker found the ammunition clip Monday morning and turned it in to school officials, who immediately imposed the lockdown, which prevents anyone from entering or leaving the school and keeps students in their classrooms.

News from © The Associated Press, 2019