How U.S. forces killed bin Laden

Abbottabad, Pakistan (CNN) — Under the cover of night, U.S. helicopters steered toward a secure compound in Pakistan on a mission to capture or kill the world’s most-notorious terrorist.

Less than 40 minutes later — early Monday morning in Pakistan — Osama bin Laden was dead, along with others inside the complex, and U.S. forces departed with the slain al Qaeda leader’s body, fulfilling a vow that originated shortly after the September 11, 2001, terrorist attacks on the United States.

“It was a staggering undertaking and there was no one else, I believe, other than an American group of military warriors who could do it. And the world is a safer place today, not only for the American people but for all people,” Vice President Joe Biden said Tuesday, in his first remarks on the death of bin Laden.

Officials on Tuesday offered new details about that raid, clarifying accounts of events given earlier.

The men who go bin Laden

U.S. military personnel, arriving on two helicopters, attacked the compound and began to clear the house, moving methodically from room to room, said White House Press Secretary Jay Carney. They were engaged in a firefight throughout the operation, he said.

There were no armed guards around the compound, according to a U.S. official who is not authorized to speak on the record.

CIA Director Leon Panetta told PBS “NewsHour” the original plan was for two Black Hawk helicopters, carrying 25 people, to go into the compound.

The first was to go over a courtyard, while the second was to go over the roof. But the first helicopter had problems and had to set down on the ground, prompting the second one to do the same, he said.

“Both teams immediately went into the compound itself. They had to breach about three or four walls in order to get in there. They were able to do that and they immediately then went into the compound itself and fought their way up to the third floor,” said Panetta.

The compound is in Abbottabad, about 50 kilometers (31 miles) north of the Pakistani capital of Islamabad. The city sits in a mountainous region that is not heavily populated. Many of the residents are army personnel.

Bin Laden was “hiding in plain sight”

When it was first built, the compound was secluded and reachable by only a dirt road, officials have said. In recent years, more residences were built around it, but it remained by far the largest and most heavily secured property in the area.

The mission ordered Friday by Obama found outer walls up to 18 feet tall topped with barbed wire, with two security gates and a series of internal walls that sectioned off different portions of the compound, senior administration officials have said.

The main structure was a three-story building with few windows facing the outside of the compound, and a third-floor terrace had a 7-foot privacy wall, they said.

Months of intelligence work determined that the compound was custom-built to hide a high-value terrorism suspect, almost certainly bin Laden.

The officials noted there was no telephone or Internet service at the dwelling, which was valued at more than $1 million, and its occupants burned their trash rather than leave it out for collection as other area residents did.

Calling the U.S. operation a surgical raid, officials said it was conducted by a small team and designed to minimize collateral damage.

Besides the bin Laden family, two other families lived in the compound, according to Carney. On the first floor of the building where bin Laden lived, two al Qaeda couriers were killed in addition to a woman caught in the crossfire, he said.

Bin Laden and his family lived on the second and third floors, and they were cleared last, with bin Laden killed toward the end of the siege, said Carney. Bin Laden was not armed but did put up resistance when U.S. forces entered the compound, he said.

According to the U.S. official, who is not authorized to speak on the record, bin Laden “didn’t hold his hands up and surrender.”

A woman in the room with him — believed to be bin Laden’s wife — rushed U.S. forces and was shot in the leg, but not killed, said Carney.

In all, said the U.S. official who sought anonymity, five of the approximately two dozen people in the compound were killed — the two couriers, the woman, bin Laden and his son.

Panetta told PBS he didn’t think bin Laden said anything to U.S. forces before he was killed.

“To be frank, I don’t think he had a lot of time to say anything. It was a firefight going up that compound and by the time they got to the third floor and found bin Laden, I think this was all split-second action on the part of the (Navy) SEALS,” he said.

Prior to the assault, U.S. intelligence officials provided detailed satellite images of the compound, which was enough to construct a replica, according to a senior defense official. The official said that team members practiced on that mock-up, to the point that they knew the height of every wall, and which gates they would have to go through.

Obama and senior administration officials have said that no U.S. forces were harmed during the operation.

According to the senior administration officials, intelligence work determined at the beginning of 2011 that bin Laden might be at the compound in Pakistan. By mid-February, the intelligence was strong enough to begin considering action.

Timeline of bin Laden operation

To discuss that intelligence and develop a plan, Obama chaired five National Security Council meetings from mid-March until late April, with the last two on April 19 and April 28 — last Thursday. The next day, on Friday, Obama gave the order for the mission, the officials said.

A U.S. official said multiple options were considered before settling on the assault.

“A bombing would not have risked American lives but it might have left questions” as to whether Bin Laden was killed, the official said. National security officials widely agreed “the best option is the one that gives proof,” the official said.

The key break involved one of the few couriers trusted by bin Laden, according to various officials. About two years ago, intelligence work identified where the courier and his brother lived and operated in Pakistan, and it took until August of last year to find the compound in Abbottabad, they said.

Trail began with bin Laden courier

“When we saw the compound where the brothers lived, we were shocked by what we saw — an extraordinarily unique compound,” one senior administration official said. “The compound sits on a large plot of land in an area that was relatively secluded when it was built. It is roughly eight times larger than the other homes in the area.”

Noting that the courier and his brother had no discernible source of wealth to live at such a property, intelligence analysts concluded the compound was “custom-built to hide someone of extraordinary significance,” the official said, adding: “Everything was consistent with what experts thought Osama bin Laden’s compound would look like.”

CNN’s Pam Benson and Chris Lawrence contributed to this report.