The hashtag #YesAllWomen was launched to allow women to share stories of misogyny in the wake of Elliot Rodger's assault on Friday in Isla Vista, near Santa Barbara, which saw him kill six people before taking his own life.
While three of Rodger's victims were men, the student had written a lengthy manifesto and posted videos online prior to the assault citing women as the cause of his rage.
In a YouTube video, Rodger spoke of his planned "day of retribution," complaining about a life of "loneliness, rejection and unfulfilled desires."
"I will slaughter every single spoiled, stuck-up blonde slut. All those girls that I've desired so much, they have all rejected me and looked down upon me as an inferior man," he says.
"#YesAllWomen because every time I try to say that I want gender equality I have to explain that I don't hate men," one poster commented.
"I was born 1918. My mother fought so she, my sister and I could vote. U must fight so ur daughters vote wisely. #YesAllWomen," wrote another.
However the hashtag quickly spawned a rival thread #NoAllMen.
"#YesAllWomen are Beautiful and #NoAllMen are not Pigs! There is Evil in the World plain & Simple there always has been always will be," one person commented.