A devastating magnitude-8.8 earthquake struck Chile early Saturday, shattering buildings and bridges, killing at least 78 people and setting off a tsunami that threatened every nation around the Pacific Ocean — roughly a quarter of the globe.

Chilean TV showed devastating images of the most powerful quake to hit the country in a half-century: In the second city of Concepcion trucks plunged into the fractured earth, homes fell, bridges collapsed and buildings were engulfed in flames. Injured people lay in the streets or on stretchers.

Many roads were destroyed and electricity and water were cut to many areas.

There was still no word of death or damage from many outlying areas that were cut off by the quake that struck at 3:34 a.m. (1:34 a.m. EST, 0634 GMT) 200 miles (325 kilometers) southwest of Santiago.

Experts warned that a tsunami could strike anywhere in the Pacific, and Hawaii could face its largest waves since 1964 starting at 11:19 a.m. (4:19 p.m. EST, 2119 GMT), according to Charles McCreery, director of the Pacific Tsunami Warning Center.

Tsunami waves were likely to hit Asian, Australian and New Zealand shores within 24 hours of the earthquake. The U.S. West Coast and Alaska, too, were threatened.

A huge wave swept into a populated area in the Robinson Crusoe Islands, 410 miles (660 kilometers) off the Chilean coast, President Michele Bachelet said, but there were no immediate reports of major damage there.

Bachelet said the death toll was at 78 and rising, but officials had no information on the number of people injured. She declared a "state of catastrophe" in central Chile.

"We have had a huge earthquake, with some aftershocks," Bachelet said from an emergency response center. She urged Chileans not to panic.

"Despite this, the system is functioning. People should remain calm. We're doing everything we can with all the forces we have. Any information we will share immediately," she said.

Powerful aftershocks rattled Chile's coast — 21 of them magnitude 5 or greater and one reaching magnitude 6.9 — the U.S. Geological Survey reported.

Bachelet urged people to avoid traveling, since traffic lights are down, to avoid causing more fatalities.

The airport for Chile's capital of Santiago airport was shut down and will remain closed for at least the next 24 hours, airport director Eduardo del Canto said. The passenger terminal suffered major damage, he told Chilean television in a telephone interview. TV images show smashed windows, partially collapsed ceilings and pedestrian walkways destroyed.

In Concepcion, nurses and residents pushed some of the injured through the streets on stretchers. Others walked around in a daze wrapped in blankets, some carrying infants in their arms.

The epicenter was just 70 miles (115 kilometers) from Concepcion, where more than 200,000 people live along the Bio Bio river, and 60 miles (95 kilometers) from the ski town of Chillan, a gateway to Andean ski resorts that was destroyed in a 1939 earthquake.

The quake also shook buildings in Argentina's capital of Buenos Aires, 900 miles (1,400 kilometers) away on the Atlantic side of South America.

Marco Vidal — a program director for Grand Circle Travel who was traveling with a group of 34 Americans — was on the 19th floor of the Crown Plaza Santiago hotel when the quake struck.

"All the things start to fall. The lamps, everything, was going on the floor. And it was moving like from south to north, oscillated. I felt terrified," he said.

Cynthia Iocono, from Linwood, Pennsylvania, said she first thought the quake was a train.

"But then I thought, oh, there's no train here. And then the lamps flew off the dresser and my TV flew off onto the floor and crashed."

"It was scary, but there really wasn't any panic. Everybody kind of stayed orderly and looked after one another," Iocono said.

In Santiago, modern buildings are built to withstand earthquakes, but many older ones were heavily damaged, including the Nuestra Senora de la Providencia church, whose bell tower collapsed. An apartment building's two-level parking lot also flattened onto the ground floor, smashing about 50 cars whose alarms and horns rang incessantly. A bridge just outside the capital also collapsed, and at least one car flipped upside down.

The quake struck after concert-goers had left South America's leading music festival in the coastal city of Vina del Mar, but it caught partiers leaving a disco. "It was very bad, people were screaming, some people were running, others appeared paralyzed. I was one of them," , Julio Alvarez told Radio Cooperativa in Santiago.

Bachelet said she was declaring a "state of catastrophe" in three central regions of the country.

She said Chile has not asked for assistance from other countries.

Several hospitals were evacuated due to earthquake damage, she said.

The Pacific Tsunami Warning Center called for "urgent action to protect lives and property" in Hawaii, which is among 53 nations and territories subject to tsunami warnings.

"Sea level readings indicate a tsunami was generated. It may have been destructive along coasts near the earthquake epicenter and could also be a threat to more distant coasts," the warning center said. It did not expect a tsunami along the west of the U.S. or Canada but was continuing to monitor the situation.

The largest earthquake ever recorded struck the same area of Chile on May 22, 1960. The magnitude-9.5 quake killed 1,655 people and left 2 million homeless. The tsunami that it caused killed people in Hawaii, Japan and the Philippines and caused damage to the west coast of the United States.

It was the strongest quake to hit Chile since a magnitude-9.5 temblor rocked southern Chile in 1960. Together with an ensuing tsunami, it killed at least 1,716 people.