(CNN) -- Two juvenile suspects were in custody Tuesday after a chemical device ruptured at SkyView Academy in Highlands Ranch, Colorado.
As a precaution, five people -- four students and one teacher -- were transported to an area hospital, the Douglas County Sheriff's Office said in a statement. All have been medically cleared and released.
Any decision on potential charges is pending. The names of the juveniles were not released. News that they had been taken into custody first spread on Twitter.
"The initial investigation was to determine if this was a malicious or accidental event. The investigation is continuing; however through our ongoing investigation we have been able to determine this was not accidental and (are) treating this as a criminal investigation," the statement read.
The sheriff's office declined to discuss specifics of the device other than to say that the chemical reaction within the container caused the device to rupture. The incident took place in a classroom, not a chemistry lab.
"Students were first evacuated and then emergency responders determined that the gym was safe -- so they were brought back where it was warm and safe," said Sgt. Ron Hanavan, a spokesman with the sheriff's office.
Classes at SkyView Academy -- a charter school with students from pre-school age through the 11th grade, according to its website -- are expected to resume Wednesday.
CNN's Carma Hassan contributed to this report.