On Friday, U.S. Special Operations forces entered Syria with the intent of capturing senior ISIS commander Abu Sayyaf and his wife Umm, the New York Times reports. The Pentagon said in a statement that Sayyaf was killed after he “engaged U.S. forces.”

According to the Times, Defense Secretary Ashton B. Carter said that Abu Sayyaf had helped manage the Islamic State’s black-market oil and gas operation. In June, ISIS was earning nearly $2 million per day refining and smuggling oil, Bloomberg Business reported. That number has reportedly fallen since air strikes began last fall.

Carter said that Umm Sayyaf—who was captured and has been moved to a military detention facility in Iraq—was also suspected of being involved in the militant group’s “terrorist activities, and may have been complicit in what appears to have been the enslavement of a young Yazidi woman rescued last night.”

Bernadette Meehan, the National Security Council spokeswoman, confirmed the rescue. “The operation also led to the freeing of a young Yazidi woman who appears to have been held as slave by the couple,” she said. “We intend to reunite her with her family as soon as feasible.”

This is only the second time U.S. troops have carried out a ground assault on Islamic State militants in Syria, the Associated Press reports. The first was a failed attempt to rescue Americans being held hostage.

No American forces were injured or killed in Friday’s mission, Carter said in his statement. The Syria Observatory for Human Rights reports that at least 19 ISIS fighters—including 12 foreigners—were killed in the raid.

Photo credit: AP Images. Contact the author of this post: brendan.oconnor@gawker.com.