Actress and singer Rose McGowan says she was sexually assaulted by a Hollywood executive, who she only refers to as a "studio head."

In a series of tweets to her 635,000 followers, the Grindhouse and Charmed star said the assault had been "an open secret in Hollywood" and she didn't report it after being discouraged by a lawyer.

"A [female] criminal attorney said because I'd done a sex scene in a film I would never win against the studio head," she wrote in one tweet posted Thursday.

Using the hashtag #WhyWomenDontReport, McGowan is one of many women speaking out about sexual assault following the release of a tape last week which caught Donald Trump making comments about groping women.

A day after the Trump tape was leaked, Canadian writer Kelly Oxford, who has more than 700,000 followers, asked women to tweet their "first assaults," using the hashtag #notokay.

What followed was a flood of responses: Oxford reported that 30 million people had read or contributed to her feed within a five-day span.

At one point, the L.A.-based author and screenwriter said she was receiving 50 tweets per minute from people about their experiences.

While Oxford maintains the #notokay campaign isn't affiliated with a political organization, McGowan is an active supporter of a social media movement called #WomenCanStopTrump. She has also become known in Hollywood for calling out sexist and questionable, but accepted, practices.

She says she was fired from her talent agency after posting audition instructions for a film last year that asked women to wear something that "shows off cleavage."