A fresh tremor rattled Ecuador before dawn Wednesday, a magnitude-6.1 magnitude jolt that set babies crying and adults pouring into the streets, fearful of yet more damage following a monster earthquake over the weekend.

It was the strongest aftershock yet following the magnitude-7.8 quake that killed more than 500 people.

The U.S. Geological Survey said the tremor was centered offshore, 15 miles west of the devastated beach town of Muisne, at 3:33 a.m. local time.

The new aftershock led some people in Portoviejo to abandon homes, even those with no apparent damage, and head through the night toward a former airport where temporary shelters have been set up.

Meanwhile, scenes of mourning multiplied all along Ecuador's normally placid Pacific coastline as people began burying loved ones and hope faded that more survivors will be found. Funeral homes were running out of caskets, and local governments were paying to bring in coffins from other cities.

In the small town of Montecristi, near the port of Manta, two children were among those buried Tuesday. They were killed with their mother while buying school supplies when the big quake struck.

The funeral had to be held outside under a makeshift awning, because the town's Roman Catholic church was damaged and unsafe. Family members wailed loudly and one man fainted as the children were laid to rest in an above-ground vault.

The National Prosecutors Office put the death toll at 553 on Wednesday but officials expected more bodies to be found, with the Defense Department reporting Tuesday that about 100 people were still missing.

The office said on its official Twitter account Wednesday that there were at least 11 foreigners among the dead.

The final toll could surpass casualties from earthquakes in Chile and Peru in the past decade.

Yet even as grief mounted, there were glimmers of hope.

In several cities, rescuers with sniffer dogs, hydraulic jacks and special probes that can detect breathing from far away continued to search for survivors among the rubble. At least six were found in Manta early Tuesday.

One of the most hopeful tales was that of Pablo Cordova, who held out for 36 hours beneath the rubble of the hotel where he worked in Portoviejo, drinking his own urine and praying that cellphone service would be restored before his phone battery died. He was finally able to call his wife Monday afternoon and was pulled from the wreckage soon after by a team of rescuers from Colombia

Cordova's wife had given up on ever seeing him again and managed to buy a casket.

"They were organizing the funeral, but I've been reborn," Cordova said Tuesday, grinning from beneath his bushy mustache in a provincial hospital. "I will have to give that coffin back because I still have a long way to go before I die."

Rescuers who have arrived from Mexico, Colombia, Spain and other nations said they would keep searching for survivors Wednesday, but cautioned that time was running out and the likelihood of finding more people alive grew smaller with the passage of every hour.

Even as authorities begin to shift their attention to restoring electricity and clearing debris, the earth continued to move. Local seismologists have recorded more than 400 aftershocks, some felt 105 miles away in the capital of Quito.

Saturday's earthquake destroyed or damaged about 1,500 buildings, triggered mudslides and left some 20,000 people homeless, the government said. It was the worst temblor in Ecuador since one in 1949 killed more than 5,000 people.

Some 13 nations are involved in the relief effort. Cuba, which suffered the deaths of three doctors in the quake itself, sent more health workers. Venezuela has flown in food and the U.S. government said Tuesday that it was sending a team of disaster experts as well $100,000 in assistance.

President Barack Obama spoke by phone with Ecuadorean President Rafael Correa on Tuesday. The White House said Obama offered condolences on behalf of the American people for lives lost.

Correa has spent the past days overseeing relief efforts and delivering supplies. He said Tuesday the quake caused $3 billion in damage, about 3 percent of gross domestic product, and rebuilding would take years.

"It's going to be a long battle," he told reporters.

After a deadly earthquake in Chile in 2010, that South American country was able to get back on its feet quickly thanks to a commodities boom that was energizing its economy. But Ecuador must rebuild amid a deep recession that has forced austerity on the OPEC nation's finances. Even before the quake, the International Monetary Fund was forecasting the oil-dependent economy would shrink 4.5 percent this year.