Administrators closed secondary schools in a Minnesota school district Monday after receiving online threats following a shooting during a homecoming game last week.

The Richfield School District said unspecified online threats were made early in the morning leading to the closure of the middle and high school, South Education Center and Richfield College Experience Program.

"While we have been partnering with police to investigate the credibility of the threats, due to the timing and the recent events outside our homecoming game, we have made the decision to close our secondary schools today," the district’s announcement said.

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The district did not disclose the nature of the threats or where they may have originated, the Star Tribune reported.

St Paul, Minneapolis, Rochester news

Administrators in Minnesota are closing secondary schools after receiving online threats. This comes after a shooting last week at a homecoming game for Richfield High School. (Fox News)

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Officials said all elementary schools will remain open because they were not the target of the threats, however police will step up patrols during the day and extra staff will be assigned.

On Friday, two people, ages 18 and 21, were wounded by gunfire outside the football field where Richfield High School was playing its homecoming game against Bloomington Kennedy.

Richfield police announced Sunday that a 16-year-old former student and a 15-year-old current student have been arrested in the shooting. No motive was released.

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Richfield is about 8 miles south of Minneapolis.