“The Avengers” stars are speaking out in protest of the Dakota Access Pipeline.

Samuel L. Jackson, Mark Ruffalo, Chris Evans and Chris Hemsworth assembled to urge fans to sign a petition calling for an end to the controversial North Dakota pipeline construction on the Standing Rock Indian Reservation.

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“Tell @POTUS to say #NoDAPL by signing the http://standwithstandingrock.net petition!!” Evans tweeted on Friday, while his cast members shared the same link across their respective Instagram accounts.

Jackson posted a video explaining acknowledging this support, stating, “I’m Samuel L. Jackson, and I acknowledge the First Peoples of America. I stand for their right to clean water, and today, I stand with Standing Rock.”

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He then directed social media followers to sign the petition at the end of the clip, which he captioned, “I’m saying #nodapl and@barackobama should too!”

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Ruffalo also posted a video to Instagram on Saturday, pledging support for protests led by Native American tribes who say the oil pipeline construction will damage their drinking water and sacred land areas.

“I acknowledge the first peoples of America,” Ruffalo said. “Today I stand with Standing Rock.”

The 48-year-old actor was just in North Dakota last week, where he shared video from a peaceful protesting that included Rev. Jesse Jackson.

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Peaceful resistance. #nodapl #standingrock

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Keeping in the “Avengers” show of solidarity, Hemsworth shared a photo of two young ladies at Standing Rock with the hashtags “#NODAPL” and “#StandWithStandingRock” overlaid on it, along with a link to the cause’s website. “I stand with the Standing Rock,” he wrote alongside the pic on Saturday. “Join me and tell @barackobama to say #NoDAPL by signing the petition.”

Last week, the Aussie actor shared a DAPL-inspire snapshot of himself in his Thor costume holding a “We Stand With Standing Rock” sign.

“Standing with those who are fighting to protect their sacred land and water,” Hemsworth captioned the Instagram.

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Standing with those who are fighting to protect their sacred land and water. #nodapl #waterislife #mniwiconi @taikawaititi I would also like to take this opportunity to raise something that has been bothering me for sometime. Last New Year's Eve I was at a "Lone Ranger" themed party where some of us, myself included, wore the traditional dress of First Nations people. I was stupidly unaware of the offence this may have caused and the sensitivity around this issue. I sincerely and unreservedly apologise to all First Nations people for this thoughtless action. I now appreciate that there is a great need for a deeper understanding of the complex and extensive issues facing indigenous communities. I hope that in highlighting my own ignorance I can help in some small way.

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Shailene Woodley, who was arrested for protesting at the pipeline last month, thanked Hemsworth for his support. “Good to see more people standing up,” she tweeted.

As the pipeline construction continues, Woodley is the only celebrity to be arrested for taking a stand against DAPL. Last month, she was honoured by the Environmental Media Association for her steadfast activism, and she spoke to ET’s Courtney Tezeno at the awards show about her arrest.

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“I don’t know if I’m fearless, but I’m definitely one of those [people] who looks fear in the face,” the 24-year-old actress passionately explained. “We are an environmental issue! Right? We are the environment. We are the soil, we come from the earth. In order to survive we need oxygen.”

See more of Woodley’s interview in the video below.

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