The D.C. Fire and EMS Department investigation into a group photo of recruits taken at the training academy in April found there was no racist intent.
The hand sign seen in the photo is similar to the nonverbal expression for "OK," but has come to be associated with white supremacy.
D.C. Fire and EMS said it was made aware of the photo this month.
Its investigation concluded the three recruits were making the gesture as part of a game and did not realize the gesture could be associated with white supremacy.
All 22 recruits in the photo were interviewed and none stated they believe there was any racist intent.
The Anti-Defamation League says on its website the "OK" hand gesture acquired a different significance in 2017 because of a hoax perpetuated on the online message board 4chan. The idea was to troll liberals by taking an innocent symbol and making them believe it was racist.
The hoax was so successful the symbol became a popular trolling tactic with right-leaning individuals and, ironically, some white supremacists, the ADL said.