A middle school teacher in New Jersey is facing multiple drug charges after allegedly overdosing on fentanyl in a classroom in November, the Westfield Police Department said. 

School Resource Officer Fortunato Riga responded to the second-floor classroom, where a nurse was treating the teacher in front of students, and gave him Narcan, a medication that can reverse an opioid overdose. 

The incident happened at Roosevelt Intermediate School on Nov. 29 of last year, but 57-year-old Frank Thompson was charged on Jan. 5 with possession of fentanyl, possession of drug paraphernalia, and endangering the welfare of children. 

Investigators later found drugs and "various items of drug paraphernalia" in a closet in Thompson's classroom, according to police. 

Thompson could not immediately be reached for comment on Sunday.

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All school resource officers in Westfield are equipped with Narcan. 

"In this case, the swift actions of Officer Riga, who is on-site at Roosevelt Intermediate each school day, proved instrumental in maintaining the safety of the students and administering potentially life-saving measures to Mr. Thompson," Westfield Police Chief Christopher Battiloro said in a statement. 

Classes were temporarily moved to a different location while the classroom was sanitized, according to Fox 5 New York. 

"While the Westfield Public School District cannot comment on personnel matters which are confidential, we will maintain a continued focus on student and staff safety and on preserving the integrity of the classroom learning environment," Superintendent Dr. Raymond González said in a statement. 

Fox News' Pilar Arias contributed to this report.