Officers say the unannounced operations were needed because of a rise in shootings, and threats of retaliation by members of a violent gang.
Four guns were also recovered during the searches and patrol stops. Police say gang members are even threatening certain officers by name.
Fresno Police Chief Jerry Dyer said, "The officers that have been named are people that are investigators that have been involved in gang investigations. They are also members of the departments that are known to gang members."
Police say the problems flared up Easter Sunday when officers confronted a murder suspect. Jerel Stanfield, 24, was shot when investigators say he ran.
Chief Dyer says a gun was found on Stanfield and the weapon was used in five shootings including a murder.
Police are now closely watching locations gang members plan to target.