At least seven people were killed Monday after a group of gunmen stormed Haiti's National Palace in an attempted coup.

News of the raid sparked violence in the capital as government supporters armed with machetes and sticks struck back by burning the homes and offices of opposition leaders.

President Jean-Bertrand Aristide and his wife not in the palace at the time of the attack and were unharmed in their suburban home in Tabarre, said National Palace spokesman Jacques Maurice.

"We have thwarted the coup, but it's not all over," Aristide said in a radio address Monday afternoon.

"The Haitian people will not have to live in hiding ever again."

Maurice said 33 gunmen first tried to attack the national penitentiary, but were rebuffed.

Then the gunmen drove to the palace, threw a grenade at the building at about 2 a.m. and opened fire as they burst in. Two police officers were killed and six others were injured, Maurice said.

During the palace attack, the gunmen used two-way radios to communicate among themselves, some speaking Creole, while others spoke in English and Spanish, Maurice said.

National Palace security head Jean Oriel said police shot and killed one gunman while regaining control of the palace at midmorning.

Police later arrested one of the alleged attackers, wounded and heavily armed, in a pickup truck on a road to the border with the neighboring Dominican Republic, police spokesman Jean-Dady Simeon said.

The rest escaped, some in a pickup truck that sped out of the palace, national radio reported. The gunmen shot and killed two passers-by as they fled, witnesses said.

A government official, speaking on condition of anonymity, said the attackers identified their leader as the former police chief of northern Cap-Haitien city, Guy Philippe, who fled to the neighboring Dominican Republic last year with seven police officers accused of plotting a coup.

But Philippe called The Associated Press from the Dominican Republic to deny involvement in the attack, saying, "it was a staged event to give a pretext for attacking the opposition."

Oriel said the gunman who died, like others in the group, was dressed in the khaki uniform of Haiti's former army, which Aristide disbanded after he returned to power in 1994.

Former soldiers have held several demonstrations against Aristide this year, calling for the re-establishment of the 7,500-strong army.

After the attack, hundreds of Aristide supporters, wielding machetes, surrounded the palace, shouting, "We'll never accept another coup d'etat."

In apparent retribution for the palace attack, Aristide's supporters torched the headquarters of the Convergence opposition alliance in the capital as well as three buildings belonging to opposition parties.

They also burned the home of opposition leader Luc Mesadieu in northern Gonaives. Two men were killed by the mob and their bodies were burned, the independent radio Haiti Inter reported.

The violence prompted the U.S. Embassy to close its doors and urge Americans in Haiti to stay at home. Airlines canceled flights to the impoverished Caribbean nation. American Airlines canceled its five flights to Port-au-Prince on Monday and morning flights on Tuesday.

"I don't know what happened at the National Palace, but it has become a pretext to massacre the opposition," said opposition leader Gerard Gourgue, who said he had gone into hiding and feared for his life.

Culture and Communication Minister Guy Paul called the burning of the opposition headquarters "a regrettable incident," but said "the people are enraged and things like that are difficult to avoid."

Aristide supporters also torched the home of opposition member Gerard Pierre-Charles in Petionville, just outside Port-au-Prince, and ransacked the French Institute, a cultural center run by the French government.

A government communiqué that aired early Monday on Radio Caraibes called on Haitians to "block the way, on top and at the bottom" to anyone who wants to destabilize the government.

Since Aristide's Lavalas Family party swept parliamentary and local elections in May 2000, Haiti has been mired in unrest with the main opposition group calling the elections fraudulent and foreign donors refusing to release desperately needed aid until results are revised.

Aristide says his mandate has been hampered by the lack of aid and calls the suspensions "economic terrorism."

Also, human rights groups have denounced Aristide's "zero tolerance" anti-crime slogan, saying some have interpreted it as license to kill thieves and government opponents.

Aristide first used the slogan in June when he called for a crackdown on rampant crime during a speech to police.

There has also been mounting grass-roots opposition to Aristide within his own party. Protesters have accused Aristide of failing to deliver on promises of basic services such as sanitation and electricity.

Aristide was first elected president in 1990 and stayed in power only eight months before the army ousted him in a coup that began Sept. 30, 1991. He was restored to power in 1994 by U.S. troops, but a term limit forced him to step down in 1996 and he was replaced by his protege, Rene Preval. Aristide began his second term in February.

The Associated Press contributed to this report.