Our Revolution, a political nonprofit that spun off of Sen. Bernie Sanders (I., Vt.) 2016 presidential campaign, lost nearly $250,000 to an email scam that same year, according to new tax documents.

The 501(c)(4) nonprofit disclosed in its 2017 tax forms, which were filed earlier this month, that they were the "victim of a Business E-Mail Compromise scam that took place in December 2016 but was not discovered until January 2017, resulting in the loss of approximately $242,000 via an electronic transfer of funds to an overseas account," Politico reported.

"Our Revolution worked with the Federal Bureau of Investigation, Our Revolution's counsel and an independent cyber-security consultant in an effort to identify the thieves and to recover the funds but, unfortunately, these efforts were unsuccessful," the group said.

The scam is known as a "CEO impersonation," and is commonly used to infiltrate a company’s computer network and then make it look it's from a vendor commonly in contact with the business, according to the FBI. The FBI wrote in 2017 that billions of dollars have been stolen as a result of the scam.

Our Revolution blamed "an international syndicate of cyber-thieves targeting nonprofit organizations globally" for the fraud, which resulted in the loss of approximately 7 percent of its total fundraising in 2016. In response, Our Revolution said in its tax filing that it will continue to "put into place additional safeguards, including both technical and human security measures, procedures and protocols." A board member told Politico that funds were found elsewhere to fulfill a promise to protest the construction of the Dakota Access Pipeline.

The money stolen had been raised as part of a campaign to aid the Standing Rock Sioux Native American tribe, which was protesting the construction of an oil pipeline near tribal land, said Lucy Flores, a former Our Revolution board member. The group still gave the tribe the $242,924 it promised, using other funds it had raised, according to its tax filing. "We’d done fundraising specifically on behalf of the tribe, and to have that money just be gone and never reach its intended purpose was unacceptable," Flores told POLITICO. "So we decided to give them the money that was raised and take the loss as an organization."

Our Revolution president Nina Turner also released a statement about the scam, saying that after the "discovery of the theft, we hired a cybersecurity firm to advise us on how to prevent these types of crimes in the future." The group's financials are coming out nearly two years later because it was set up as a "social welfare" nonprofit instead of a political action committee. PACs have to regularly file reports with the Federal Election Commission or Internal Revenue Service, disclosing their fundraising and spending history.

The group self-publishes donor names on its website but does not include the donation amounts. It raised $3.42 million in 2016 after its founding in July of that year and another $3.45 million in 2017, the majority of which was from small, online contributions. It spent nearly $3.2 million in 2017, plus over $1 million on salaries. Our Revolution also spent over $489,000 on grants to other organizations and $258,000 on digital messaging.