Feral...

feral
ˈfɛr(ə)l,ˈfɪə-/
adjective
(especially of an animal) in a wild state, especially after escape from captivity or domestication.
"a feral cat"

synonyms: wild, untamed, undomesticated, untrained, unused to humans;

antonyms: tame, pet
resembling or characteristic of a wild animal.
"his teeth were bared in a feral snarl"

synonyms: fierce, ferocious, vicious, savage, aggressive, tigerish, wolfish, predatory, menacing, threatening, bloodthirsty
"he gave a feral snarl"

(of a young person) behaving in a wildly undisciplined and antisocial way.
"gangs of feral youths"


I think the last one pretty much covers it... perhaps without the young part.