Australian troops backed by a warship arrived in East Timor to boost security Tuesday after rebel attacks on the country's two top leaders left the president in "extremely serious" condition with gunshot wounds.

The government declared a state of emergency amid fears of more unrest and political turmoil triggered by the assassination attempts Monday against President Jose Ramos-Horta and Prime Minister Xanana Gusmao.

Surgeons operated on Ramos-Horta for three hours overnight to remove bullet fragments and repair his chest wounds, Dr. Len Notaros, the general manager of the Royal Darwin Hospital, told the Australian Broadcasting Corp.

"His condition remains extremely serious but by the same token, stable," Notaros said. "The next few days will be the telling point. I believe he is extremely lucky to be alive."

Ramos-Horta, who won the 1996 Nobel Peace Prize for his nonviolent resistance to the decades-long Indonesian occupation, was shot in the chest and stomach close to his house by rebel soldiers Monday, officials said.

His guards returned fire, killing wanted rebel leader Alfredo Reinado and one of his men.

Gunmen attacked Prime Minister Xanana Gusmao's motorcade an hour later. The former guerrilla fighter escaped unhurt.

East Timor is a country of 1 million people that won independence from Indonesia in 2002 after a U.N.-sponsored ballot. The poor nation has struggled to achieve stability, especially since an outbreak of violence and political turmoil in 2006.

The first of a planned contingent of 120 Australian troops touched down in the capital of Dili to strengthen a foreign military peacekeeping mission that has been in the country since the 2006 unrest.

Earlier, about 30 Australian police officers arrived to boost a U.N. force already on the half-island country, while a Navy warship also moored off the coast in sight of Dili harbor.

Acting President Vicente Gutterres announced the two-day emergency in an address on national television. The order bans demonstrations, gives police extended powers of search of arrest and calls for a nighttime curfew.

"Our country is right now in an extraordinary situation where a state of emergency will bring us back to normality," Gutterres said. "I ask for your help."

As he spoke, international soldiers and police patrolled Dili's streets and searched cars at roadblocks. Most shops and businesses were open and traffic was normal. There were no immediate reports of unrest.

East Timor's army chief, Taur Matan Ruak, questioned how the attack happened given the heavy presence of foreign police and troops stationed on the tiny island.

"How is it possible that cars transporting armed people have entered the city and executed an approach to the residences of the prime minister and president without having been detected?" he asked journalists.

Ramos-Horta, 58, first underwent surgery at an Australian army hospital in East Timor before being sedated, attached to a ventilator and airlifted to the hospital in the northern Australian city of Darwin.

Notaros said Ramos-Horta's wounds indicated he had been shot two or three times. The most serious wound was to the lower part of his right lung near his liver, and would likely require more surgery. There was also a risk of sepsis infection, Notaros said.

The bullet fragments will be handed to Australia Federal Police for the investigation into the shooting, Notaros said. At least one fragment was being left in his body, and was not thought to be life-threatening, he said.

Reinado was among 600 mutinous soldiers dismissed by the government in 2006 — a move that triggered gunbattles between security forces that later spilled over into gang fighting and ethnic unrest.

At least 37 people were killed and more than 150,000 people forced from their homes in the unrest, which also led to the resignation of the country's first post-independence prime minister.

Reinado was arrested but escaped from prison after several months.

He was charged with murder in connection with the unrest, but remained in hiding and threatened insurrection against the government — a stance that made him popular among some disaffected East Timorese youth.

"What we are going do now is try to get back our confidence after the loss of our commander, our teacher and our guide," said Joao Zito Marques, a 24-year-old student. "He was a good revolutionary struggling to find truth and justice."

Despite the outstanding charges, Ramos-Horta had met with Reinado on several occasions in recent months to try to persuade him to surrender.