Hundreds of search and rescue experts from 13 countries are joining Ecuadorian rescue teams, the nation's foreign minister says, to try to save the lives of anyone who survived a magnitude 7.8 earthquake on Saturday and remains trapped beneath the rubble.

But hour by hour, the odds dwindle that anyone has survived this long.

Foreign Minister Guillaume Long tweeted on Monday night that more than 650 international search experts were already assisting in Ecuador, and more were on their way.

The Associated Press wrote that rescuers were in "a race against time."

"Complicating rescue efforts is the lack of electricity in many areas, meaning noisy power generators must be used, making it harder to hear people who might be trapped beneath rubble," the wire service writes.

The death toll is north of 400, and expected to rise.

There were some joyful scenes on Monday, the AP writes:

"In the port city of Manta, a group of about 50 rescuers working with sniffer dogs, hydraulic jacks and a drill managed to free eight people trapped for more than 32 hours in the rubble of a shopping center that was flattened by Saturday night's quake."The first rescue took place before dawn, when a woman was pulled headfirst from a nearly 2½-foot hole cut through concrete and steel. Firefighters applauded as she emerged from the debris, disoriented, caked in dust and complaining of pain but otherwise in good health."Another uplifting scene played out in nearby Portoviejo, where a cellphone call to a relative from under the debris of a collapsed hotel led searchers to Pablo Cordova, the hotel's administrator. Once he was gingerly removed, he was immobilized and hauled away on a stretcher, his hands waving in the air in a sign of appreciation to cheering onlookers." 'Since Saturday, when this country started shaking, I've slept only two hours and haven't stopped working,' said Juan Carranza, one of the firefighters leading the rescue effort in Portoviejo."

The BBC wrote several years ago that, while in rare instances people can live for weeks in rubble, the U.N. calls off most search efforts after five to seven days, after no survivors have been found for one or two days.

Journalist Julia Symmes Cobb is in Pedernales, a beach town among the hardest hit of Ecuador's communities, reporting on the damage.

She tells NPR's Morning Editionthat rescue operations there have started to turn from hopeful to heart-wrenching.

"There have been some rescues of living victims here in Pedernales, but most of the rescues now are pulling out remains from the wreckage," she says.

Eighty percent of the buildings in Pedernales were damaged in the quake, Cobb says.

"Many people have lost their homes, lost their businesses, lost any — any — worldly possessions," she says. "So a lot of people have been made homeless, and a lot of people were sleeping on the streets, on mattresses or in hammocks, whatever they could sort of rig up.

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