WASHINGTON -- Yesterday's terrorist bombings threaten to push an already fragile global economy into widespread recession, smashing consumer confidence and disrupting basic commercial functions such as air travel and financial markets. "A full-blown global recession is highly likely," Sung Won Sohn, chief economist at Wells Fargo & Co., predicted in a report yesterday afternoon.

Economic policy makers did their best to ensure calm. Shortly after noon, the Federal Reserve issued an emergency statement stating that the central bank's system was "open and operating" and that officials were "to meet liquidity needs" of the global financial system, echoing a similar declaration issued during the 1987 stock-market crash.

Treasury Secretary Paul O'Neill issued a statement from Tokyo, saying: "In the face of today's tragedy, the financial system functioned extraordinarily well, and I have every confidence that it will continue to do so in the days ahead." No major problems were reported in the banking system, though branches did close in New York. The stock, bond, and commodity all closed and will remain closed today.

"I'm sure that central bankers everywhere will do everything possible to maintain calm and seek to ensure the world economy functions smoothly in the face of this horrendous deed," Federal Reserve Bank of New York President William McDonough told Dow Jones Newswires by telephone from Basel, Switzerland, where he was attending meetings at the Bank of International Settlements. Fed Chairman Alan Greenspan was on his way back to the U.S. from those meetings, but his airplane returned to Switzerland after the attacks.

Economists groped in vain for historical precedents to help evaluate the potential impact of such a shocking, tragic event on the economy. "I don't know where to look for analogies," said Alan Blinder, economics professor at Princeton University. "Confidence-shaking events usually have transitory negative effects on consumer spending. But we've never seen anything like this that I can think of."

The most recent comparable event was the 1990 Gulf War, involving a spike in oil prices and dispatch of U.S. troops to the Middle East, which depressed confidence and played a decisive role in bringing about the 1990-91 recession.

But many economists said this event is likely to be more severe because of the much greater loss of life on U.S. soil. In 1990, travel was depressed by fears of a terrorist attack. This time, the entire air-travel system has been shut down by actual attacks. "One might expect [confidence]) . . . will plunge much like they did when the Gulf crisis began in August of 1990. The weakness might be more severe because this impacts Americans more directly, it's on our soil," said Ray Stone, economist at Stone & McCarthy Research Associates.

In addition, he said, "the economy looks more fragile going into this episode than it did back in 1990." Business investment and exports are falling, unemployment has risen sharply and stock prices are sinking. The impact of the tragedy on confidence could severely undermine consumer spending, which had been the economy's remaining bulwark.

Consumers, Mr. Stone added, will likely "spend less on big-ticket items such as autos, as well as things directly affected. Air traffic likely will be lower, people less willing to visit Washington or New York City or other large cities, less likely to visit sporting events where they're worried about a terrorist attack."

But others played down any long-term consequences. "There's always speculation that these disasters have extreme economic consequences, but they rarely do," said Edward Leamer, a professor of economics and statistics at University of California at Los Angeles and director of the UCLA Anderson Business Forecast. Disasters such as the Northridge, Calif., earthquake in 1994 "hardly show up in the economic data. I would expect this to be one of those events."

Another negative could be a rebound in oil prices as political tensions rise again in the Mideast. Brent crude-oil futures surged $3.60 to $31.05 a barrel after the attacks, before closing at $29 a barrel in Europe. But the secretary-general of the Organization of Petroleum Exporting Countries said the group is prepared to take necessary measures to stop world oil prices from spiking. Business investment, already contracting, could get hurt further. "With these four hijackings of commercial East-to-West Coast flights, how can anyone get on a plane to conduct and close business?" said David Readerman, an analyst at investment bank Thomas Weisel Partners in San Francisco. "A lot of phone and video-conferencing with clients. Increase spending on security of all kinds: hardware, software, etc. [It's] truly stunning -- we've all flown on these flights, been in the World Trade Center with clients. [It's] difficult to comprehend the scale and scope of loss of life."

The initial impact on the economy may be more akin to a hurricane or earthquake: Economic activity in affected sectors and regions will slow sharply, but there might be some offsetting increases in spending to repair the damage.

Carolyn Gorman, vice president in Washington for the Insurance Information Institute, a trade group, said the attacks amount to the most-costly man-made catastrophe ever in the U.S. The other major ones have been the Los Angeles riots, $775 million in insured loss; the 1993 World Trade Center bombing, $510 million; and the Oklahoma City bombing, $125 million.

The longer-term impact will depend partly on how economic policy makers respond. The blow almost certainly guarantees that the Fed -- and central banks around the world -- will cut interest rates even more than had been expected in order to maintain the smooth working of the world financial system. The tragedy will also lead to more fiscal-policy support for the economy, ending the bitter partisan bickering that was steering politicians toward embracing growth-damping budget surpluses.

President Bush has argued for easing tight fiscal limits in the case of recession or war. The first was already perilously close before yesterday's events. The second, in some form, is here. Defense spending in particular -- which had been considered a likely victim of the obsession with fiscal austerity -- will likely get broad, bipartisan support.

"This is when we need leadership," said Mr. Sohn of Wells Fargo. "How well the White House, Congress and the Federal Reserve manage this crisis will determine how short or long the damage is going to be."

Rebecca Buckman and Sheila Muto contributed to this article.