U.S. personnel overnight killed a key Islamic State leader in charge of the group's oil and gas operations in a raid in eastern Syria, the White House said Saturday.

A team of Delta Force commandos slipped across the border from Iraq under cover of darkness Saturday aboard Black Hawk helicopters and V-22 Osprey aircraft, according to a U.S. defense official knowledgeable about details of the raid.

The U.S. team killed leader Abu Sayyaf and 11 other ISIS fighters and captured his wife, Umm Sayyaf. A senior defense official told Fox News that while no Americans were injured or killed in the operation, some of the fighting was hand-to-hand and that Sayyaf used women and children as human shields.

"It was a real firefight - a no kidding old school firefight," a senior defense official said.

Ancient Assyrian texts and other priceless artifacts were recovered as well as what the defense official called a "treasure trove" of intelligence materials, such as cell phones, laptops and documents.

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Sayyaf was a senior ISIS leader whose roles included overseeing illicit oil and gas operations -- key sources of revenue for the terror group, according to the White House. He also was allegedly involved with the group's military operations.

U.S. officials said it was likely, given Abu Sayyaf's position, that he knew about more than just the financial side of the group's operations and was also was targeted for his known association with the group's leader, Abu Bakr al-Baghdadi.

A U.S. official told The Associated Press his removal probably has temporarily halted ISIS oil-revenue operations, critical to the group's ability to carry out military operations in Syria and Iraq and to govern the population centers it controls.

Sayyaf's wife also was an ISIS member and is believed to have played an important role in terror activities. Umm Sayyaf was taken to a secure location in Iraq where she is being interrogated, a senior U.S. defense official told Fox News.

The commando operation also led to the freeing of a young Yezidi woman who appears to have been held as a slave by the couple. 

The White House said President Obama authorized the operation as soon as he and his national security team developed sufficient intelligence and were confident the mission could be carried out successfully.

Defense Secretary Ash Carter said he ordered U.S. Special Operations Forces into Syria’s al-Amr region to capture Sayyaf and his wife.

ISIS has over roughly the past year made a swift and unexpected rise in Syria and Iraq, taking territories and using captured assets to finance its deadly operations, which have including the online publishing of beheadings.

Syrian state media earlier reported that government forces killed at least 40 ISIS fighters, including a senior commander in charge of oil fields, in an attack Saturday on the country's largest oil field -- held by ISIS.

It identified the commander as Abu al-Teem al-Saudi.

The Britain-based Syria Observatory for Human Rights confirmed an oil field attack, saying at least 19 ISIS members, including 12 foreigners, were killed. The group did not say who carried out the attack.

"Normally, when we go in, we kill a lot of people." a U.S. official said.

A U.S. official told Fox News that the U.S. Army's elite Delta Force carried out the mission. Delta -- known formally in U.S. special operations circles as the Combat Applications Group, or "CAG" --  is the Army's version of the U.S. Navy's SEAL Team 6. 

Delta Force is based out of Fort Bragg, in North Carolina.

Fox News' Lucas Tomlinson, Jennifer Griffin and The Associated Press contributed to this report.