Two St. Louis-area police officers and a police dog had to be administered the opioid overdose reversal medication Narcan after they were exposed to what was believed to be fentanyl.

St. Charles County Police spokeswoman Val Joyner said Tuesday that both officers and the dog are recovering.

An officer made a vehicle stop around 10:30 a.m. Monday. An occupant admitted possessing methamphetamine. Another officer arrived with a drug-sniffing dog to search the vehicle. Both car occupants were taken into custody.

The dog got sick about 30 minutes later, and the handler administered Narcan. Two hours later, both officers got sick, and they required Narcan.

Joyner says it's unclear how the officers were exposed to the drug. The department's officers have been carrying Narcan since 2015.