VADNAIS HEIGHTS, Minn. - A cache of guns, ammunition and an explosive device at a Vadnais Heights home.

That’s what authorities say they uncovered after they say there was a threat made at a school by a 13-year-old student.

RELATED: Police: Student threat leads to gun, bomb cache in Vadnais Heights

Mark Stowe says the report stemmed from a conversation his grandson was having with other kids at the school. He said there was a “rolling” conversation in which someone said, “Would you bring a gun to school?” Stowe says his grandson replied, “'I would just shoot it up. Ha. Ha.' And that is what was said. It was not meant hostile at all.”

Ramsey County authorities would not elaborate on the specific threat Friday but said, “A student was threatened by another student.”

“The student that was threatened subsequently told their parent about the threats to them," said Sheriff Jack Serier.

A call to the executive director of the school, the Academy for Sciences and Agriculture, was not returned on Saturday.

When authorities searched the home of the student they found several firearms, a “ballistic vest,” thousands of rounds of ammunition and at least one explosive device. Sheriff Serier says many of the weapons were unsecured.

“What I think happened was a total overreaction at the school,” Mark Stowe says. “Someone should have taken them aside and explained to them the seriousness of what happened in Florida.”

Stowe says his 13-year-old grandson, who was arrested for allegedly making terroristic threats, is also autistic and described him as “mild” on the autism spectrum.

This would be the second such case in a 10-day period in the Twin Cities metro. On Feb. 21, a student at the Orono school district made a “threat of gun violence,” which caused a lockdown for several hours.

The student, who was autistic, has been charged. Community members have since created a GoFundMe page expressing their sympathy. One woman writing on the page, I have a 19 year old son with Autism. I fear every day that he may end up in the legal system and he functions at a nine year old level. We are praying for your son and your family!”

Authorities in Vadnais Heights arrested both parents of the 13-year-old in Vadnais Heights. They’re facing a misdemeanor charge of negligent storage of a firearm.

“You ask, 'Why do you have a big stash of guns?'” Mark Stowe presented the question after reading media reports of the incident. “It’s not a stash. It’s not an arsenal. It’s a collection. ... My son and I were even talking about starting a small store. Many of these weapons were passed down through our family.”

Ramsey County Sheriff Jack Serier said Friday that “this had all the ingredients for tragedy to follow.”

Stowe said he believed his son and daughter-in-law were being held in jail through the weekend and that this was an overreaction in light of the school shooting in Florida and the national gun debate.

Stowe also said he believed the “explosive” that investigators say the retrieved was a “WWII smoke canister.”

Ramsey County authorities wouldn’t elaborate on what type of explosive was found.

“We’re not the bad guys.” Stowe said. “I understand you can’t yell fire in a crowded theater. There are certain things you don’t say. But it was not a threat."