NEW YORK — Even as hospitals began the grim accounting of the dead and injured from the airborne onslaught that toppled the World Trade Center, investigators on Wednesday sought answers in Florida and elsewhere to an unspeakable question: Who could have done this?
The financial capital remained closed after the attack on the twin towers and the Pentagon. The federal government said the ban on air travel would not be lifted before noon and that it would take a while for schedules to return to normal.
Thousands were feared dead. Wednesday morning, Mayor Rudolph Giuliani said there were 41 known deaths — clearly, a tiny fraction of the dead — and 1,700 known injuries. He said 235 uniformed officers, including police and firefighters, remained unaccounted for.
The mayor said rescuers were still in contact with one person buried in the rubble.
The search for answers was unflagging. The focus was on Islamic terrorist Osama bin Laden, who denied involvement, though he "thanked Almighty Allah and bowed before him when he heard this news" of the attacks, according to a Palestinian journalist.
Law enforcement officials were said to be looking at possible bin Laden supporters in Florida and Massachusetts. They were aided by an intercept of communications between his Florida supporters and harrowing cell phone calls from victims aboard the jetliners before they crashed.
The FBI executed search warrants in Davie in Broward County north of the Miami area, the South Florida Sun-Sentinel of Fort Lauderdale reported, quoting Miami FBI spokesman Judy Orihuela.
The FBI was also seeking search warrants in Daytona Beach, where a car was towed by authorities.
Tuesday's assault on American government and finance led President Bush to place the military on its highest state of alert.
Smoke still drifted from the ravaged Pentagon, and authorities said they did not expect to find more survivors.
But the government went back to work Wednesday, its political leaders, diplomats and soldiers leaving no doubt the terrorist assault will be answered. "We will go after them," Secretary of State Colin Powell vowed.
The Navy said the aircraft carrier USS George Washington was in position Wednesday off the coast of New York.
Americans across the country remained on alert. For a second day, baseball's major leagues canceled all games. And Lou Dorr, an FAA spokesman, said passengers could expect tough security measures at reopened airports, suggesting that they arrive two hours early for flights.
A day earlier, as workers poured into Wall Street, a hijacked jet tore through one of the 110-story twin towers. Another followed, striking the other tower in a fireball 18 minutes later. By 10:30 a.m., both towers had collapsed in horrifying clouds of gray smoke.
A third jet struck the Pentagon at 9:40 a.m. A fourth hijacked airliner plummeted to earth about 80 miles southeast of Pittsburgh.
The final death toll may not be known for weeks. The four planes alone had 266 people aboard. Authorities said between 100 and 800 people were believed dead at the Pentagon. Thousands of people worked at the trade center, and many were inside when it collapsed.
"Thousands of lives were suddenly ended by evil, despicable acts of terror," Bush said.
In New York, firefighter Rudy Weindler spent nearly 12 hours trying to find survivors and only found four — a pregnant woman sitting on a curb and three others in the rubble of a building in the trade center complex.
"I lost count of all the dead people I saw," Weindler said. "It is absolutely worse than you could ever imagine."
U.S. officials said the attacks were carried out with military precision.
The planes were each on cross-continental routes and thus carrying a heavy load of flammable fuel. They struck the buildings high up and on the corners, stymieing firefighters' ability to contain the ensuing blaze and blocking escape for some tenants.
"There are so many other buildings that are partially destroyed and near collapse," said Weindler, the firefighter. "There are a lot of fires still burning."
Three top fire department officials were among those who died. One of them, Ray Downey, chief of special operations command, led a team of New York firefighters to Oklahoma City in 1995 after the bombing of the Alfred P. Murrah Federal Building.
Cranes 120 feet tall and bulldozers were brought in to clear the streets on Tuesday. Rescue workers were armed with pickaxes and shovels.
"I must have come across body parts by the thousands," said Angelo Otchy, a mortgage broker who came in with a National Guard unit from Dover, N.J., to help dig through the debris.
City paramedic Louis Garcia said: "There's 2 feet of soot everywhere, and a lot of the vehicles are running over bodies because they are all over the place. There were people running up to us who were totally burned — no hair, no eyebrows."
Parag Papki went to five hospitals on Tuesday looking for his brother, Ganesh Ladkat, who worked on the 104th floor of the trade center. He was sent to a center set up to account for the missing.
"They asked me what was he wearing, any body marks, stuff like that," Papki said after filling out a form. "Since afternoon, I am searching."
Normally 50,000 people work in the twin towers, but the first attack came when many workers were not yet in their offices. Officials estimated that 10,000 to 20,000 people were in the buildings when the first plane crashed. Many fled, rushing down dozens of flights of stairs before the second jet hit and the towers collapsed.
The 1,350-foot-tall towers, which survived a terrorist bombing in a basement parking garage in 1993, were reduced to a pile of stone and steel about five stories high. A hazy, brownish-gray cloud was all that could be seen where the gleaming rectangular towers used to loom.
Much of lower Manhattan, a center of world finance that includes Wall Street and the stock exchanges, was cordoned off. Every aspect of daily life in the city was disrupted, from phone service to subways.
An election primary that had been scheduled for Tuesday, to determine the Democratic and Republican candidates for mayor, was indefinitely postponed.
The Empire State Building — along with schools and many offices — was closed Wednesday as a city filled with world-famous landmarks came to grips with its vulnerability.
Thousands of dazed New Yorkers walked out of Manhattan on Tuesday across the Brooklyn Bridge. They couldn't help looking back at the two huge pillars of smoke, filling the gap where the trade center once stood between the Statue of Liberty and the Empire State Building.
Many of the evacuees were covered in gray ash. Strangers patted each other on the back as they passed on city streets. Some were numb with shock — others cried hysterically.
Eyewitnesses recalled seeing people jump from windows of the tower high in the sky — including a man and a woman who held hands as they plunged to their deaths.
A few people on the hijacked planes managed to make cell phone calls, in which they said terrorists armed with knives were taking over the jets.
A London-based Arab journalist said followers of bin Laden warned three weeks ago that they would carry out a "huge and unprecedented attack" on U.S. interests.
The Boston Herald, quoting a source it did not identify, reported that authorities had seized a car at Logan airport that contained Arabic-language flight training manuals. The source said five Arab men had been identified as suspects, including a trained pilot.
At least two of those men flew to Logan on Tuesday from Portland, Maine. Gov. Angus King said the two men apparently were using New Jersey driver licenses but little else was known about them. They left behind a rental car that was impounded in the Portland area.
The luggage of one of the men who flew to the airport Tuesday didn't make his scheduled connection. The Boston Globe reported the luggage contained a copy of the Quran, an instructional video on flying commercial airliners and a fuel consumption calculator.