With the World Trade Center and Pentagon in flames, Arab governments expressed condolences to the United States today and condemned such attacks on civilian lives. But some of their citizens celebrated in the streets over a comeuppance they feel the world's sole remaining superpower deserved for its support of Israel.

Thousands of Palestinians in the West Bank and Gaza Strip cheered the attack, distributing candy and firing weapons in a show of glee over what they described as a retaliatory blow against U.S. cooperation with Israel. Palestinians in refugee camps in Lebanon fired weapons into the air in celebration.

"The people here are gloating over the American grief," said Emad Salameh, a 29-year-old taxi driver in Gaza. "Apache helicopters, tanks and all kinds of destructive weapons have been killing Palestinian infants and women. . . . Palestinians have been crying and suffering, and now it is time for Americans to cry and suffer."

"This is revenge from Allah," said Khaled Saada, a 25-year-old clothing store owner in Gaza City.

The reaction in Israel was starkly different. Many Israelis said they felt as if the attacks had occurred in Israel itself and expressed hope that now Americans will better understand Israel's tough tactics toward Palestinians.

The outpouring among Arabs contrasted sharply with official condemnations issued by several Arab leaders, including the Syrian government of President Bashar Assad, President Hosni Mubarak of Egypt and the Palestinian leader, Yasser Arafat.

"I send my condolences, the condolences of the Palestinian people to American President Bush and his government and to the American people for this terrible act," Arafat told reporters in Gaza. "We completely condemn this serious operation. . . . We were completely shocked."

Mubarak called the attacks in New York and Washington "horrific" and added in a televised statement: "Egypt firmly and strongly condemns such attacks on civilians and soldiers that led to the deaths of a large number of innocent victims."

But the street reactions in Lebanon and Palestinian-run areas of the Gaza Strip and the West Bank reflected a popular sentiment expressed often by Arabs frustrated over U.S. policy and, to some extent, by their leaders.

Arab leaders and citizens have expressed growing anger over U.S. political support and military aid for Israel, regarding Washington as implicated in the violence that has claimed 700 lives over the last year, most of them Palestinians. Islamic fundamentalist groups, including Osama bin Laden's al Qaeda, are also offended by the U.S. military presence in Saudi Arabia, the birthplace of Islam, while U.S.-led economic sanctions and airstrikes against Iraq have become increasingly unpopular among Arabs.

An editorial this week in the Saudi daily al-Jazirah, for instance, cautioned that "latent Arab forces" might lash out against U.S. interests in ways that Arab states would not.

"Of course, we are sad that so many innocent people have to die, but the Americans need to come down from their tower and see the reaction to what their government does," said Mahmoud Hassanein, a shop owner in Maadi section of Cairo.

"It is all related" to U.S. support for Israel, said Bakir Haisam, owner of textile shop in the upscale Amman neighborhood of Shmeisani. "Here, most of the people will appreciate such a thing. In a way I think it is a good thing. Perhaps it is a little improper . . . but it is complicated."

Although there was no proof, many Israelis assumed the culprits in the attacks on U.S. soil came from the Islamic world. Now, they said, Americans would finally understand Israel's predicament and think twice before condemning Israel's assassinations of Palestinian leaders and other attacks on Islamic militants involved in the year-old uprising against Israeli occupation of the West Bank and Gaza Strip.

Partly in sympathy, partly in relief, many Israelis said the long-standing political, military, personal and psychological bonds between the two countries would grow tighter than ever.

"I feel sad because now the Americans will be like us -- scared, angry, not safe," said Ilanit Amsalem, 36, a teacher in Jerusalem. "I always thought of the U.S. as some sort of a Disneyland, innocent, naive and childlike, a place that didn't have all the scars that we have. Now they'll be cynical like us and they'll start looking for revenge, like we do."

"Now the Americans won't judge us," said Shuki Barkan, a student in Jerusalem. "Now they'll get it -- that these terrorists, all of them, aren't human beings. They'll do anything. And so maybe [the United States] won't be so quick to condemn us. It was easy for them to be so super-righteous when [terror] didn't affect them."

The official Israeli reaction was to assume a defensive crouch nearly as broad as America's own, assuming that the coordinated attacks in the United States might presage attacks on the Jewish state. Israeli airspace was closed to all flights originating overseas unless they had Israeli security guards on board, as do flights on El Al, the national carrier. Israel evacuated its embassy and consulates in the United States, leaving only key personnel.

The air force went on high alert for any unauthorized planes heading toward Israeli airspace. Extra security was added at Ben-Gurion International Airport near Tel Aviv, the U.S. Embassy in Tel Aviv and the U.S. Consulate in Jerusalem. Israel, well rehearsed in public disasters, offered to send rescue teams to the United States.

Hockstader reported from Jerusalem.

Israeli Foreign Minister Shimon Peres tells reporters that Israel has declared a national day of mourning, adding, "We are with America." Palestinians at a refugee camp in southern Lebanon celebrate the attacks.Israeli Jews watch news coverage of the attacks at a Jerusalem restaurant.Palestinian leader Yasser Arafat condemned the attacks and sent condolences to President Bush. "We were completely shocked," he said.