Much damage was reported in the cities of Manta, Portoviejo and Guayaquil, which are all several hundred kilometers from the epicenter of the quake that struck shortly after nightfall Saturday.

But the loss of life seemed to be far worse in isolated, smaller towns closed to the center of the earthquake.

In Pedernales, a town of 40,000 near the epicenter, soldiers put up a field hospital in a stadium where hundreds of people prepared to sleep outside for a second straight night. Downed power cables snaked across the streets with no prospect of electricity being restored soon, making it unsafe for many to return to their homes.

The town's mayor said looting broke out Saturday night amid the chaos but with the arrival of 14,000 police and soldiers to towns in the quake zone the situation appeared more under control.

President Rafael Correa, who cut short a trip to Rome to oversee relief efforts, declared a national emergency and urged Ecuadoreans to stay strong.

"Everything can be rebuilt, but what can't be rebuilt are human lives, and that's the most painful," he said in a telephone call to state TV before departing for Manta, where he arrived just before nightfall to be briefed by aides.

More than 3,000 packages of food and nearly 8,000 sleeping kits were being delivered Sunday. Ecuador's ally, Venezuela, and neighboring Colombia, where the quake was also felt, organized airlifts of humanitarian aid. The European Union, Spain, Peru and Mexico also pledged aid.

Rescuers scrambled through ruins in the provincial capital Portoviejo, digging with their hands trying to find survivors.

"For god's sake help me find my family," pleaded Manuel Quijije, 27, standing next to a wrecked building. He said his older brother, Junior, was trapped under a pile of twisted steel and concrete with two relatives.

"We managed to see his arms and legs. They're his, they're buried, but the police kicked us out because they say there's a risk the rest of the building will collapse," Quijije said angrily as he looked on the ruins cordoned off by police. "We're not afraid. We're desperate. We want to pull out our family."

Electricity mostly remained out in Manabi province, the hardest-hit region, as authorities focused on finding survivors.

"Compatriots: Unity, strength and prayer," the vice president told a throng of people in Manta as he instructed them on how to look for survivors. "We need to be quiet so we can hear. We can't use heavy machinery because it can be very tragic for those who are injured."

On social media, Ecuadorians celebrated a video of a baby girl being pulled from beneath a collapsed home in Manta.

But fear was also spreading of unrest after authorities announced that 180 prisoners from a jail near Portoviejo escaped amid the tumult after the quake.

Shantytowns and cheaply constructed brick and concrete homes were reduced to rubble along the quake's path. In the coastal town of Chamanga, authorities estimated than 90 percent of homes had damage, while in Guayaquil a shopping center's roof fell down and a collapsed highway overpass crushed a car. In Manta, the airport closed after the control tower collapsed, injuring an air traffic control worker and a security guard.

In the capital, Quito, terrified people fled into the streets as the quake shook buildings. One resident shot a video of his lamps and hanging houseplants swinging wildly for more than 30 seconds as the building rocked back and forth. The quake knocked out electricity in several neighborhoods and a few homes collapsed, but after a few hours power was being restored.

Among those killed was the driver of a car crushed by an overpass that buckled in Guayaquil, the country's most populous city. Two Canadians were also among the dead. The city's international airport was briefly closed.

The government said it would draw on USD$600 million (21 billion baht) in emergency funding from multilateral banks to rebuild.

Hydroelectric dams and oil pipelines in the OPEC-member nation were shut down as a precautionary measure but there were no reports of damage to them.

The U.S. Geological Survey originally put the quake at a magnitude of 7.4 then raised it to 7.8. It had a depth of 19 kilometers. More than 135 aftershocks followed, one as strong as magnitude-5.6, and authorities urged residents to brace for even stronger ones in the coming hours and days.

The quake was about six times as strong as the most powerful of two deadly earthquakes on the other side the Pacific, in the southernmost of Japan's four main islands. A magnitude-6.5 earthquake struck Thursday near Kumamoto, followed by a magnitude-7.0 earthquake just 28 hours later. Those quakes killed 41 people and injured about 1,500, flattening houses and triggering major landslides.

Susan Hough, a seismologist at the USGS, said evidence exists that extremely large earthquakes can trigger other earthquakes at large distances and that within close distances the frequency of quakes are frequently clustered. But she said there appears no direct relationship between the quakes on opposite sides of the Pacific.

"Nobody has ever demonstrated statistically significant temporal clustering of large quakes worldwide," she said in an email. "Maybe there is something more going on than what we understand."

Story: Dolores Ochoa, Allen Panchana / Associated Press

"We're trying to do the most we can but there's almost nothing we can do," said Gabriel Alcivar, mayor of Pedernales, a town of 40,000 near the epicenter. He pleaded for authorities to send earth-moving machines and rescuers as dozens of buildings in the town were flattened, trapping residents among the rubble. He said looting broke out amid the chaos but that authorities were too busy trying to save lives to assert order.

"This wasn't just a house that collapsed, it was an entire town," he said.

Vice President Jorge Glas said in a televised address late Saturday that there were initial reports of 41 dead in the cities of Manta, Portoviejo and Guayaquil — all several hundred kilometers (miles) from where the quake struck shortly after nightfall.

The quake was the strongest to hit Ecuador since 1979, Glas said. On social media photos circulated of homes reduced to rubble, the roof of a shopping center torn apart and supermarket shelves shaking violently. In Manta, the airport was closed after the control tower collapsed, injuring an air traffic control worker and a security guard.

In the capital Quito, hundreds of kilometers away, people fled to the streets in fear as the quake shook their buildings. The quake knocked out electricity in several neighborhoods and six homes collapsed but after a few hours the situation appeared under control and power was being restored, Quito's Mayor Mauricio Rodas said.

"I'm in a state of panic," said Zoila Villena, one of many Quito residents who congregated in the streets. "My building moved a lot and things fell to the floor. Lots of neighbors were screaming and kids crying."

More than 10,000 members of the security forces were being mobilized to provide assistance but Glas said accessing what he described as the "disaster" center was difficult due to landslides.

Among those killed was the driver of a car crushed by an overpass that buckled in Guayaquil, the country's most populous city. The city's international airport was also briefly closed. Hydroelectric dams and oil pipelines in the OPEC-member nation were shut down as a precautionary measure but so far hadn't reported any damaged.

President Rafael Correa, who is in Rome after attending a Vatican conference Friday, called on Ecuadoreans to stay strong while authorities monitor events.

He said on Twitter he had signed a decree declaring a national emergency but that the earliest he could get back to Ecuadoris Sunday afternoon. He said that there were "dozens of dead" from the earthquake.

The Pacific Tsunami Warning Center said hazardous tsunami waves are possible for some coasts. While the government hadn't issued a tsunami alert, towns near the epicenter were evacuated as a precautionary measure. Glas later said it was safe for coastal residents to return to their homes.

An emergency had been declared in six of Ecuador's 24 provinces, while sporting events and concerts were cancelled until further notice nationwide.

"It's very important that Ecuadoreans remain calm during this emergency," Glas said from Ecuador's national crisis room.

The USGS originally put the quake at a magnitude of 7.4 then raised it to 7.8. It had a depth of 19 kilometers. At least 36 aftershocks followed, one as strong as 6 on the Richter scale, and authorities urged residents to brace for even stronger ones in the coming hours and days.

The quake comes on the heels of two deadly earthquakes across the Pacific, in the southernmost of Japan's four main islands. A magnitude-6.5 earthquake struck Thursday near Kumamoto, followed by a magnitude-7.3 earthquake just 28 hours later. The quakes have killed 41 people and injured about 1,500, flattened houses and triggered major landslides.

Story: Gonzalo Solano / Associated Press