( CNN ) -- Police cars and fire trucks surrounded Jefferson County Open School in Colorado Monday , as hazmat crews decontaminated students outside -- spraying them down , fully clothed , in cordoned-off sections under a blue tent . Students coming in after recess had reported eye and skin irritations . Thirty kids and a teacher 's aide were eventually treated for symptoms similar to an allergic reaction , according to CNN affiliate KUSA . A handful were taken to the hospital . The rest were evacuated to a church down the street . The K-12 Colorado school remained closed on Tuesday as investigators tried to figure out what `` toxic irritant '' had been released on the playground . They quickly figured out that it was n't fertilizer or pepper spray , KUSA reports . Six habanero chili peppers caused this hot mess . Investigators found the spicy fruits scattered in the wood chips near the playground , school district communications director Lyyn Setzler told CNN . It is n't known how the peppers got there , she said . Habaneros generally score between 100,000 and 350,000 units on the Scoville scale , which measures chili pepper hotness . `` The scale is actually a measure of the concentration of the chemical compound capsaicin , which is the active component that produces the heat sensation for humans , '' according to ChiliWorld.com . For comparison , jalepeno peppers usually score 2,500 to 5,000 units . When you grind ( or step on ) habanero peppers , capsaicin particles can be released into the air . Breathing them in or getting them in your eyes can cause a burning sensation . `` As a person who grows some painful peppers , I have learned the hard way to take heed when handling them , '' says CNN Eatocracy editor Kat Kinsman . `` It 's all fun and games until you get some pepper juice in your eye , and then it 's as if the sun is exploding . '' The spiciest dish I ever ate . The school is washing down the playground equipment and surfaces that may have been exposed to the pepper oil , KUSA reports . The wood chips are also being replaced . All the students who were brought to hospital for evaluation were released the same day , and all are fine , according to the local fire department . Setzler says the school expects to re-open tomorrow morning . CNN 's Stefan Simons contributed to this story .
Jefferson County Open School was evacuated on Monday . The school is located in the town of Jefferson, about 30 miles west of St. Louis. Investigators found six habanero chili peppers on the playground .