Fresno police say officers arrested a man with warrants around 1 pm near Kings Canyon and Peach.
While taking the suspect to the Fresno County Jail, one of the officers began to feel sick.
Officials say the officer pulled over and passed out.
The officer was given Narcan and taken to the hospital, where he is expected to make a full recovery.
The suspect was also taken to the hospital to be checked out.
Investigators say they believe the officer might have been exposed to a substance on the suspect's clothing.