ADAMS COUNTY, Colo. – At least five Adams City Middle School students were taken to a hospital Monday for evaluation after they ate marijuana-infused candy, the school and district said.

Around 2:15 p.m. Monday, several students reported feeling nauseous and dizzy and told the health clerk at the school they had eaten candies.

The school said in a letter home to parents that first responders suspected the students had eaten marijuana edibles and that the school decided to call an ambulance “out of an abundance of caution.”

An Adams 14 district spokesperson said that five students were evaluated for “cautionary reasons” and that officials did not believe they were in any medical danger. The district said it was unknown how the edibles got into the school nor how many students actually ate the candies.

Students at the school were released to parents at the end of the day. Commerce City police said Tuesday the department had an open criminal investigation into the incident but that they had not identified the source of the edibles as of 11 a.m.