Story highlights 10-year-old Blake Kroll raised $20,000 for a children's hospital

Kroll initially pledged to donate $500 before businesses and individuals also chipped in

(CNN) There are a lot of ways a 10-year-old boy might spend $500. But when Blake Kroll auctioned off his pig for $500 at the county fair, he donated his earnings to Children's Hospital of Wisconsin.

It didn't stop there.

Kroll's mother, Kim, told CNN that when others saw her son's generous donation they raised their paddles at auction to chip in as well. First, one person offered to cover the $500 that Blake was donating.

Then, Kim said, "it was like a chain reaction. It's phenomenal because we are small community. Everyone knows everybody."

Within minutes, 31 businesses had donated thousands of dollars.

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