(CNN) -- A massive magnitude 8.8 earthquake rocked Chile early Saturday, killing at least 122 people and triggering tsunami warnings for the entire Pacific basin.
Chilean President Michelle Bachelet said she expected the death toll to rise.
"We are taking all the necessary measures at this time," she said.
Officials did not give any information on the number of those injured. The full extent of the damage was not yet known, although there were reports of collapsed buildings and hundreds of people in the streets.
The capital of Santiago lost electricity and basic services including water and telephones. Bachelet said regional hospitals had suffered damage; some were evacuated. A major bridge connecting northern and southern Chile was rendered inoperable, and the Santiago airport was shut down for at least the next 24 hours.
Chilean television showed buildings in tatters in Concepcion, with whole sides torn off. At least two buildings there were engulfed in flames, and roads in the city were broken up, video showed.
Television Nacional de Chile reported that only three stories of a 15-story building remained standing.
Numerous aftershocks -- including one of magnitude 6.9 -- were felt within hours of the initial quake, the U.S. Geological Survey said.
"There are really aftershocks like every hour," said Felipe Baytelman, speaking to CNN from Santiago.
The quake's epicenter was located off the coast of Maule, about 200 miles southwest of Santiago. It struck at 3:34 a.m. (1:34 a.m. ET), when most people were sleeping.
"This is a major event. This happened near some very populated areas," said Randy Baldwin, a geophysicist with USGS. "With an 8.8 you expect damage to the population in the area."
The earth's rumbling was felt by millions in Chile and in parts of Argentina, as well. Some buildings in the Argentine capital, Buenos Aires, were evacuated.
Bachelet declared areas of catastrophe, similar to a state of emergency, that will allow her to rush in aid. She said the town of Chillan -- which was destroyed by a killer quake in 1939 -- was one of the worst affected.
U.N. Secretary-General Ban Ki-moon was trying to contact the Santiago-based U.N. Economic Commission for Latin America and the Caribbean for an assessment of the earthquake and information on staffers.
As daylight broke and more of the quake damage could be surveyed, yet another threat loomed: a tsunami.
The Pacific Tsunami Warning Center issued a tsunami warning, the highest level of a tsunami alert, for the entire Pacific region, including Hawaii and places as far away as Russia and Japan.
"We have information of high-altitude waves that could be seen in the following hours," Bachelet said. "We are evacuating people in lower areas to higher ground." California and Alaska are under a tsunami advisory.
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"An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines near the epicenter within minutes and more distant coastlines within hours," the National Weather Service said in a statement.
USGS geophysicist Victor Sardina said several tsunami waves had come ashore along the Chilean coast; the largest was recorded at 9 feet near the quake's epicenter.
The earliest estimated arrival for a wave that could affect Hawaii was 12:46 a.m. local time (6:46 p.m. ET). But evacuations of coastal areas were to begin at 6 a.m. (12 p.m. ET).
Saturday's quake comes just a few weeks after an earthquake devastated parts of Haiti. That quake was magnitude 7.0. The Chilean quake, at magnitude 8.8, was a thousand times stronger. An earthquake displaces 64 times more energy for each additional point on the magnitude scale.
Check out the world's biggest earthquakes since 1900
The full extent of the damage was not yet known, although there were reports of collapsed buildings and hundreds of people in the streets. The ceiling of a parking lot in the fashionable Las Condes neighborhood of Santiago came crashing down, crushing at least 50 cars.
CNN showed pictures from TV Nacional, a 24-hour network that broadcasts across the country. CNN Chile has suffered damage to its broadcast facilities, although it is still actively newsgathering.
Santiago resident Leo Perioto jumped out of bed in his apartment at the top of a six-story building.
"The whole building was shaking," he said. "The windows were wobbling a lot. We could feel the walls moving from side to side."
Glass shattered at the Santiago Marriott Hotel, but there appeared to be no structural damage, said Alessandro Perez.
Anita Herrera at the Hotel Kennedy in Santiago said electricity was out and guests were nervous.
"Our hotel is built for this," she said. "In Chile this happens many times."
The U.S. State Department said all its personnel were accounted for, and that no decision has been made about Secretary of State Hillary Clinton's planned trip next week to five Latin American countries, including Chile.
Coastal Chile has a history of deadly earthquakes, according to the USGS. Since 1973, there have been 13 quakes of magnitude 7.0 or higher.
Saturday's epicenter was just a few miles north of the largest earthquake recorded in the world: a magnitude 9.5 quake in May 1960 that killed 1,655 and unleashed a tsunami that crossed the Pacific and destroyed much of the Hilo Bay area of Hawaii.
The earthquake that caused the 1960 tsunami occurred off the west coast of South America. The waves reached the Hawaiian Islands in about 15 hours. This tsunami caused little damage elsewhere in the islands, but the Hilo Bay area was hard hit. Sixty-one people lost their lives and about 540 homes and businesses were destroyed or severely damaged. The wave heights in Hilo Bay reached 35 feet compared to only 3-17 feet elsewhere.