(AP) — When helicopters carrying some 50 U.S. commandos thumped onto the ground in Syria an hour after midnight, the raiders confronted a houseful of extremists and children.

Baby comforts were inside — a stuffed bunny, a blue plastic swing, a crib. So was the paraphernalia of violence — such as the bomb Abu Ibrahim al-Hashimi al-Qurayshi is said by U.S. officials to have used to blow up himself, his family and perhaps others in his immediate proximity.

It was an audacious raid in an extremist stronghold of northwest Syria, months in the works and executed with the understanding that children might die as well as the hunted IS chief if the building’s occupants did not get out when given the chance to leave.

The apparent suicide bombing came before or early in a two-hour gun battle Thursday. First responders said 13 people died, six of them children. No U.S. commandos were wounded, military officials said.

President Joe Biden, who ordered the raid, said the world is rid of a man he described as the driving force behind the “genocide of the Yazidi people in northwestern Iraq in 2014,” when slaughters wiped out villages, thousands of women and young girls were sold into slavery and rape was used as a weapon of war.

“Thanks to the bravery of our troops, this horrible terrorist leader is no more,” Biden said.

THE PREPARATION

Over months of planning, U.S. intelligence first had to locate al-Qurayshi’s whereabouts and understand his movements — or lack thereof. They concluded he rarely, if ever, left his family’s third-floor quarters except to bathe on the building’s roof.

Anticipating that al-Qurayshi could well choose death by self-detonation if cornered by U.S. forces, U.S. officials commissioned an engineering study-from-afar of the three-story, cinder-block building to see if it would collapse in that event and kill everyone inside.

They concluded that enough of the building was likely to survive such a blast to spare those not near him.

They constructed a tabletop model of the house and in December set it up in the Situation Room, the ultra-secure White House command and communications post where presidents and their national security aides manage crises.

The second floor of the Syrian house, also white, was occupied by a lower-ranking Islamic State leader and his family. The ground floor, partly a basement, housed a family unconnected to the Islamic State and unaware of al-Qurayshi’s presence or significance, U.S. officials said.

Biden was first briefed in depth more than a month ago by operational commanders after U.S. forces were satisfied they would find al-Qurayshi — also known as Haji Abdullah — where they did.

The Islamic State, which once controlled most of the territory in Iraq and parts of Syria, has been attempting to regenerate, and staged its most ambitious operation in years when it seized a prison in northeast Syria last month holding at least 3,000 IS detainees.

For all his brinkmanship with Russia, as it amasses its forces for a possible new invasion of Ukraine, Biden could not afford to take his eyes off IS.

On Tuesday morning, he met Defense Secretary Lloyd Austin and Gen. Mark Milley, chairman of the Joint Chiefs of Staff, in the Oval Office and gave the go-ahead. Wednesday evening in Washington, Biden was in the Situation Room, monitoring a live feed of the mission as it unfolded.