The deputy reported tightness in the chest with a restricted ability to breathe, along with other symptoms, and exhibited confusion and the inability to speak coherently, the sheriff's office said.
The sheriff's office said a student may have been burning what at this time are believed to be counterfeit M30 pills containing fentanyl.
The Willamina School District notified parents and the affected classroom was ventilated and thoroughly cleaned, the sheriff's office said.
Multiple documented fentanyl overdoses have happened the county in the last four days, one of which was fatal, according to the sheriff's office. Because of that, authorities are concerned about a potential regional distribution of a particularly potent batch of counterfeit pills.