RIO DE JANEIRO — A deadly 8.8-magnitude earthquake struck central Chile early Saturday, ripping apart buildings, highways and bridges and leaving a path of smoky rubble across a long swath of this earthquake-tested country before sending waves rumbling across the Pacific Basin.

At least 300 people died, according to local news services that quoted the director of Chile’s emergency management office, and more than 1.5 million people were displaced. The death toll was expected to rise, particularly around Concepción, Chile’s second-largest metropolitan area, which is roughly 70 miles from the quake’s center.

There, cars lay mangled and upended on streets littered with telephone wires and power cables. A new 14-story apartment building fell, while an older, biochemical lab at the University of Concepción caught fire.

In the nearby port of Talcahuano, a giant wave flooded the main square before receding and leaving behind a large fishing boat on the city streets.

“It was terrible, terrible,” said Adela Galaz, a 59-year-old cosmetologist who said glasses and paintings fell to the floor of her 22nd-floor apartment in Santiago, 200 miles from the quake’s center. “We are grateful to be alive.”

President Michelle Bachelet, speaking at a news conference Saturday night, called the quake “one of the worst tragedies in the last 50 years” and declared a “state of catastrophe.”

While this earthquake was far stronger than the 7.0-magnitude one that ravaged Haiti six weeks ago, the damage and death toll in Chile are likely to be far less extensive, in part because of strict building codes.

The quake, tied for the fifth largest in the world since 1900, set off tsunami waves that swamped some nearby islands before moving across the Pacific. Hawaii began evacuations before dawn, but by early afternoon there — more than 15 hours after the earthquake first struck 6,500 miles away — the fears of a destructive wave had passed. Countries including Japan and the Philippines were on alert and ordered limited evacuations in anticipation of waves hitting Sunday.

Chileans were only just beginning to grapple with the devastation before them, even as more than two dozen significant aftershocks struck the country.

In Santiago, the capital, residents reported having been terrified as the city shook for about 90 seconds. Some people ran screaming from their downtown apartments, while car alarms and sirens wailed during the middle of the night. At least one apartment building collapsed, according to local media, and one highway buckled, turning over cars.

“We are in panic because it has been trembling all day,” said Cecilia Vial, 65, an interior decorator in Santiago, who dashed out of her apartment only to return at night because she had nowhere else to go.

“We cannot go against nature,” she said. “This is something that nature did.”

Paul E. Simons, the United States ambassador to Chile, said in a telephone interview from Santiago that people he spoke with at the embassy said those 90 seconds “felt like five minutes.” He added: “It was definitely an emotional experience.”

Mr. Simons said that although the United States had offered aid, Chile’s government had not yet requested assistance. All international relief groups were on standby, and the International Federation of Red Crosses and Red Crescents said the Chilean Red Cross indicated that it did not need external assistance at this point.

Although there were long lines at supermarkets and gas stations, and pictures of buildings chipped and large holes in the roads, the capital city, according to residents there, was mostly calm by the late afternoon Saturday. But the scene was grimmer in Concepción, and surrounding areas to the south.

In Chillán, 69 miles from Concepción, a crumbling wall allowed 300 prisoners to escape and incite a riot with the guards, according to La Tercera, the nation’s largest newspaper. The police captured 60 but more than 200 were still at large, the newspaper reported on its online service. With major highways and bridges destroyed, and slabs of concrete jabbing diagonally into the air, transportation slowed or was halted altogether.

Most of the damage was in Concepción, near where the world’s largest recorded earthquake, a 9.5 trembler, struck in 1960.

Earlier on Saturday, the effects of the earthquake began rippling through the Pacific, where a huge wave had swept into a populated area in Robinson Crusoe Island, 410 miles off the Chilean coast. Authorities there said at least four people had been killed.

Across the Pacific, the first hemisphere-wide tsunami warning since 1964 was issued.

In Hawaii, when the swells finally did hit, they were not as high as feared.

President Obama spoke briefly outside the White House on Saturday afternoon, expressing concern for the country and saying the United States would offer aid in rescue and recovery efforts.

“Early indications are that hundreds of lives have been lost in Chile and the damage has been severe,” Mr. Obama said. He told Mrs. Bachelet that the United States was ready to help if needed. “We will be there for her should the Chilean people need assistance,” he said

State Department officials said that Secretary of State Hillary Rodham Clinton, who had been planning a trip to South America beginning on Monday, was also contacting Mrs. Bachelet, with whom she has long had warm personal relations.

Ban Ki-moon, the United Nations secretary general, also offered his condolences, as well as longer-term aid should Chilean officials signal the need for it.

The earthquake struck at 3:34 a.m. in central Chile, centered roughly 200 miles southwest of Santiago at a depth of 22 miles, the United States Geological Survey reported.

The most powerful earthquake ever recorded was also in Chile: a 9.5-magnitude quake struck in the spring of 1960 and set off a series of deadly tsunamis that killed people as far away as Hawaii and Japan.

But that earthquake in Chile, which killed nearly 2,000 people and left more than two million homeless at the time, prepared officials and residents in the region for future devastating effects.

Shortly after a 7.8-magnitude earthquake struck in Valparaíso in 1985, the country established strict building codes, according to Andre Filiatrault, the director of the Multidisciplinary Center for Earthquake Engineering Research at the University at Buffalo.

“Chile is not a stranger to earthquakes,” he said Saturday in a telephone interview. He said the government code was called the Earthquake Resistant Design of Buildings, and Chilean engineers have been very active in world earthquake conferences.

“There is a lot of reinforced concrete in Chile, which is normal in Latin America,” Professor Filiatrault said. “The only issue in this, like any earthquakes, are the older buildings and residential construction that might not have been designed according to these codes.”

This was in direct contrast to Haiti’s building codes and infrastructure, which was unprepared for the Jan. 12 earthquake, he added.

“If you are considering this magnitude is 8.8 — which is close to 100 times greater than the Haitian quake, I would be very surprised if the death tolls come close,” Professor Filiatrault said."