Anti-transgender activists have been pushing a conspiracy theory claim that the YouTube shooting was “transgender violence.”

Four people were injured at the YouTube headquarters in California on Tuesday when Nasim Najafi Aghdam, a video maker upset that the company had stopped paying her ad money, opened fire on workers.

Aghdam, who was born in Iran and had tens of thousands of followers on social media, took her own life after the attack.

In the wake of the attack, conspiracy theorists have pushed a number of theories about the shooter’s background- and anti-trans feminist campaigners have latched onto a claim that she was transgender.

Both far-right anti-LGBT activists and feminist campaigners who oppose trans rights have latched onto the theory, claiming, without evidence, that Aghdam was a “transgender woman” because the vegan bodybuilder does not look “feminine enough”.

Jennifer James, an activist who heads a campaign to force the UK’s Labour Party to ban transgender women from women-only positions, was among those to make the claim.

She wrote: “The youtube shooter was a man. This was male violence. Name the problem. Men can shoot, rape kill but we have to ‘respect pronouns’. No.”

Ms James doubled down: “So many ppl are still insisting shooter was female. Despite videos, photos, description from youtube HQ. witness.. Why are women forbidden to name male violence? Why are we expected to lie about a killer’s sex?”

Another anti-trans feminist on Twitter who goes by the monicker ‘GenderCritXX’ pushed the surreal conspiracy theory.

The user wrote: “They say the shooter is female. Women would never do such a thing. You can guarantee they are not actually female and are just another TIM [Trans-Identified Male].”

The conspiracy theory also spread on internet forum Mumsnet, which has recently become an organising platform for anti-transgender campaigners – with contributors insisting Aghdam was a “Trans-Identified Male.”

One appalled user wrote: “Seriously no wonder people accuse Mumsnet of transphobia.”

The site eventually opted to delete several threads on the subject, with messages from admins insisting the threads were “too speculative at this stage” and in “poor taste.”

There is no evidence that Nasim Aghdam was a transgender woman.

San Bruno Police Department, which attended the scene describes the shooter as “Nasim Najafi Aghdam, a thirty-nine year old female resident of San Diego.”

Its initial report of the incident specifies that officers found “a deceased female with a gunshot wound that is believed to have been self-inflicted.”

Nasim had a vast online presence but most of her social media accounts and websites have been pulled down in the wake of the shooting.

However, her since-deleted Instagram account initially included photos of her as a child.

A 2014 FBI study found that women were responsible for six out of 160 “active shooter incidents” in the United States between 2000 and 2013.

Noor Salman, the wife of the shooter who killed 49 people in Orlando’s Pulse gay club in June 2016, was last week found not guilty of helping him plan the attack.