OSHKOSH, Wis. — Five people have been arrested in unrelated school threats in Oshkosh and Fond du Lac.

Authorities say an 18-year-old man and two boys, ages 17 and 15, were arrested for threats that shut down Oshkosh’s two public high schools Thursday. The schools have reopened.

Police say those threats were made in 911 calls to the Waupaca County Sheriff’s Office on Wednesday and Thursday.

In what is believed to be an unrelated incident in Fond du Lac, authorities say two high school students, ages 17 and 16, were arrested after a threatening note was found Wednesday in a hallway.

Police say the note made reference to vulgar rap lyrics and a threat to the school on Thursday. Police presence in and around Fond du Lac High School was increased.