A police officer in Santiago controls the traffic beside an elevated highway that collapsed in Saturday's earthquake. (David Lillo/Associated Press)

An 8.8-magnitude earthquake, one of the largest ever recorded, tore apart houses, bridges and highways in central Chile on Saturday and sent a tsunami racing halfway around the world.

Chileans near the epicentre were tossed about as if shaken by a giant, and authorities said at least 300 people were dead.

The quake was felt as far away as Sao Paulo in Brazil — 900 kilometres to the east. The full extent of damage remained unclear as scores of aftershocks — one nearly as powerful as Haiti's devastating Jan. 12 earthquake — shuddered across the disaster-prone Andean nation.

President Michele Bachelet declared a "state of catastrophe" in central Chile and said the death toll was rising.

"We've learned that it was a shallow thrust earthquake, which means it had the potential to cause a tsunami, which it did in this case," said Jessica Sigala of the U.S. Geological Survey.

"The earthquake in Chile released about 500 times the amount of energy that the earthquake in Haiti did," she told CBC News.

Haiti's massive earthquake on Jan. 12 killed more than 200,000 people and levelled 38 per cent of the capital of Port-au-Prince.

"With this new quake, the oceanic crust went under Chile and as it did this, it created this tremendous amount of energy that pushed out toward the ocean and then that water caused the wave to occur," Sigala said.

Tsunami warnings were issued over a wide area, including South America, Hawaii, Japan, Taiwan, Indonesia, the Philippines, Russia and many Pacific islands.

Tsunami waves reached Hawaii around noon local time, but there were no reports of damage. The Pacific Tsunami Warning Center cancelled its tsunami warning for Hawaii a couple of hours later.

A huge wave reached a populated area in the Robinson Crusoe Islands, 660 kilometres off the Chilean coast, Bachelet said. There were no immediate reports of major damage there, she added.

Centred southwest of Santiago

In Chile's capital, Santiago airport was shut down Saturday and will remain closed for at least the next 24 hours, airport director Eduardo del Canto said. The passenger terminal has suffered major damage, he told Chilean television in a telephone interview.

"Early indications are that hundreds of lives have been lost in Chile and damage is severe," U.S. President Barack Obama said. He offered to send resources to help in the rescue and recovery efforts once the Chilean government asks for U.S. help.

Chilean television showed images of destroyed buildings and damaged cars, with rubble-strewn streets and toppled pedestrian walkways.

The quake struck at 3:34 a.m. local time (1:34 a.m. ET) and was centred 325 kilometres southwest of the capital, Santiago, at a depth of 35 kilometres, the U.S. Geological Survey reported.

In the hours after the 90-second tremor, the U.S. Geological Survey reported 11 aftershocks. The strongest was a magnitude 6.9.

Tall building, roads, bridges collapse

A 15-storey building collapsed in Concepcion, a city of 670,000 along the Bio Bio River, located 115 kilometres from the epicentre.

Residents walk past debris after an 8.8-magnitude earthquake struck central Chile early Saturday. (Aliosha Marquez/Associated Press)

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. The national Fine Arts Museum was badly damaged.

A highway overpass in the capital collapsed, trapping at least eight cars. Several more lay overturned near the rubble. An apartment building's two-level parking lot was flattened onto the ground floor, smashing about 50 cars, whose alarms and horns rang incessantly.

Collapsed roads and bridges complicated north-south travel.

In the coastal city of Vina del Mar, the earthquake struck just as people were leaving a disco, Julio Alvarez told Radio Cooperativa in Santiago. "It was very bad, people were screaming, some people were running, others appeared paralyzed. I was one of them."

Bachelet said she was declaring a "state of catastrophe" in three central regions of the country, and that while emergency responders were waiting for first light to get details, it was evident that damage was extensive.

She encouraged people to stay home and not travel unless they had to.

Map: Chilean earthquake

View Chile earthquake in a larger map

Hospitals evacuated

Several hospitals have been evacuated due to earthquake damage, she said, and communications with the city of Concepcion remained down. She planned to tour the affected region as quickly as possible to get a better idea of the damage.

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

With files from The Associated Press