Image copyright Getty Images Image caption A closed nuclear plant is located next to the school

A US middle school has closed for the remainder of the school year after authorities found it was contaminated with radioactive chemicals.

Officials say a nearby air monitor detected enriched uranium and neptunium-237 at Zahn's Corner Middle School in Piketon, southern Ohio.

There are more than 300 pupils and 25 staff at the school.

A nearby nuclear plant made weapons-grade uranium for the Department of Energy until its closure in 2001.

"There's just not a playbook in how we deal with this," superintendent Todd Burkitt told local broadcaster WLWT. "We're kind of writing the script as we go."

Scioto Valley Local School District said the school would remain shut until "the source, extent, level of contamination, and potential impacts to public health and environment can be determined."

According to their letter, both enriched uranium and neptunium are "contaminants of concern" at the nearby Portsmouth Gaseous Diffusion Plant.

The plant made nuclear materials for the US Department of Energy and the US nuclear weapons programme between 1954 and 2001.

"After the Cold War, weapons-grade uranium enrichment was suspended and production facilities were leased to the private sector," the Department of Energy says on its website. "In 2001, enrichment operations were discontinued at the site."

Operations are now under way to decommission and decontaminate the site.

CNN reports that scientists from the Northern Arizona University took air, water and soil samples in the area as authorities set to work creating a waste disposal facility nearby.

The scientists' report, combined with the Department of Energy's annual assessment, convinced the local district to shut the school.

Local councilwoman Jennifer Chandler told CNN that five children in the district had been diagnosed with cancer in the past five years, three of whom have died.

"You don't want to make a claim that you can't back up," she said. "How is this caused? Is this a genetic cancer? Is this an environmental cancer? I'm not a medical professional.

"This isn't a game, you know. These are people's lives."