Amy Schumer recalled the moment she heard there was a shooting in a theater playing her movie "Trainwreck."

On July 23, a man opened fire inside a Lafayette, Louisiana theater, while Schumer was still on a press tour for the movie. She tells Vanity Fair magazine's May issue that she remembers having a bunch of missed calls from her publicist that night.

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"I was laughing before I called her back, because I thought it was going to be like a sex tape [had surfaced] or something. So I was kind of laughing, like ready to … And then she told me there had been this shooting," Schumer explains in the publication's cover story. "It really … I don’t know. It’s like when the Dark Knight shooting happened, and in Paris. The idea of people trying to go out and have a good time -- you know, like looking forward to it? I don’t know why that makes me the saddest.”

Starting to cry, the 34-year-old comedian adds, "So my publicist told me. And then I put on the news. I was by myself in a hotel, and I was just like, I wish I never wrote that movie."

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Schumer says that when her friends attempted to comfort her by telling her that she wasn't at fault, it only made it worse. "I just felt helpless and stupid," she says.

The "Inside Amy Schumer" star contacted the victims' families and made donations on their behalf. She also started working with her cousin, Senator Chuck Schumer, to change the gun laws in America. "I got a call, and he was like, ‘Amy, this is your cousin Chuck.’ And I said, ‘I hope this is you asking me to help with guns,’" she shares. "He laughed. ‘Yeah, that’s what this is.’ I was like, ‘Let’s go. Let’s do it.'"

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When ET spoke with Schumer in December, she was adamant that she would not be silent about this issue. "I am someone who has a voice right now, and I feel really passionately about it, and it's so heartbreaking," she said. "It's just, like, enough. So, if not me, then who? And I hope other people will follow suit."