Authorities say they found no threat at a school locked down on Alaska's Kodiak Island after a student was overheard talking about shooting up the campus.

Kodiak police say in a statement that officers searched the high school and middle school campus and conducted interviews Tuesday morning.

Police say officers and school officials "located the source of the statement and determined there was no credible threat to the school."

The school and other buildings were reopened mid-morning. 

Kodiak Police Chief Ronda Wallace did not immediately respond to a request for further information about the investigation.

But she told The Associated Press earlier Tuesday that police went to the school around 9 a.m. after officials reported a student's statements overheard by a substitute teacher. A nearby elementary school was also placed under lockdown.

Wallace said the student was heard saying "something to do with losing it and shooting up the school."

Kodiak police said in a statement issued Tuesday that more information about the lockdown will be provided after all
relevant information is collected and responders are debriefed. 

Kodiak is located about 400 kilometres southwest of Anchorage. There are about 650 students at Kodiak High School.