It was still dark when the small squad of intelligence agents began staking out the apartment block where suspected Al Qaeda members had been living for several months. Lightly armed, they decided to wait until daylight.
Fewer than 20 men, the agents and a backup unit of Pakistani police made their move at midmorning, easily capturing two men.
The date was fitting: Wednesday, Sept. 11, 2002.
Then a bloody gunbattle erupted, and hand grenades and smoke bombs were thrown.
In the raid, according to U.S. officials, Ramzi Binalshibh, was captured. He was reputedly the logistics and financial planner of the attacks a year earlier in the United States and a prominent figure on the FBI's most wanted list.
Several versions, with minor variations, exist for events leading up to the raid on the five-story apartment block by Pakistani agents of the InterService Intelligence, or ISI, along with CIA operatives. They were related by officials who spoke only on condition of anonymity.
No U.S. personnel were hurt in the raid, American officials said.
A senior Pakistani official said the lead to the apartment came from a pair of raids conducted the evening before. In those raids, two Burmese men and several Yemenis were captured.
Another official said a Burmese forger captured late last month with false travel documents brought the security men Tuesday night to an apartment in the building whose owner lived abroad. For a few rupees (dollars) to the watchmen, the forger could use it as an overnight safe house for "guests."
Another official said a satellite telephone call was traced to the house.
All versions agree that information discovered in these raids Tuesday led the investigators around 3 a.m. to the apartment building in the Defense area of south Karachi, a middle class neighborhood of rows of buildings with three floors of apartments above street-level shops.
At about 9:30 a.m., the police team seized the two men as they left the building. But the arrest was seen from the apartment above, and the other militants grabbed their weapons.
They threw two hand grenades on the raiders, who had to retreat under fire. It was only then that reinforcements were summoned -- by a neighbor who heard the gunfire and called the police hotline.
By the time reporters arrived on the scene close to 10 a.m., hundreds of police were in the surrounding streets and lanes, and on rooftops with a clear view of the building. The cement wall around the top-floor window was peppered with bullet marks.
At least two militants had moved up to the roof and taken position on the northern and western corners, shielded by a low cement barrier. Police tried to fire tear gas canisters onto the roof, but several missed and bounced back onto the policemen below.
Under a screen of smoke grenades, the police made their way to the pavement outside the shops, where they were protected by a three-foot overhang. Commandos in body armor made their way slowly up the stairs.
A woman carrying what appeared to be an unconscious infant was led out of the building. She was dressed in a long robe that could have been Afghan. A senior official said the woman provided key information on the number of gunmen inside.
Later, after more policemen entered the building, a second woman with a child was led out by two men in plain clothes.
"There are more inside. I don't know. I don't know," she said, speaking Urdu and clearly a Pakistani.
During a brief lull in the shooting, police called on the gunmen to surrender. "You can't get away," shouted someone. In response came what is often taken as an Islamic battle cry: "Allahu Akhbar," or God is great. The shooting started again.
Within a few minutes, police led a beefy, curly-haired man through the doorway, his arms tightly bound behind him and a sweaty shirt tied around his face as a blindfold.
Inside, a rapid burst of gunfire was heard amid another shout of Allahu Akhbar. Officials said tear gas fired through the window had forced the militant to open the door of the room where he was hiding, and he was gunned down.
Then, a security man brought another prisoner to the window and flashed a sign that the battle was over. Police in the street unleashed a fusillade of gunfire in celebration, emptying their magazines in the air.
The prisoner, in a blue shirt and with his face covered from his forehead to the tip of his nose, was dragged outside and pushed through a cordon of police and journalists.
Seemingly defiant, he shouted slogans in Arabic and tried to wave his fist in the air. His full lips and bearded chin matched photographs of Ramzi Binalshibh.