BASALT, Colo. (CBS4)- Police in Basalt ordered everyone to evacuate Basalt High School after some form of chemical was intentionally discharged inside the school.
About three dozen people were exposed to the chemical just after noon near the bathrooms off the main hallway.
That area has been cordoned off while officers search for the device.
Officers said the chemical appears to be some sort of tear gas and not pepper spray.
Those affected are experiencing severe stomach cramping and eye watering. Pepper spray would have more of an impact on sinuses.
Although 36 victims were affected only two students were taken to the hospital. Others were treated and released at the school and advised to go home for the day.
Some teachers were among those exposed, including one woman who is pregnant. She is expected to be okay.
School was in session throughout the day after the initial evacuation but everyone must walk around to the back of the school to enter because the main hallway was cordoned off.
Police are interviewing witnesses as part of their investigation.
Basalt is between Glenwood Springs and Aspen on Highway 82.