The strongest earthquake to hit Ecuador in decades has flattened buildings and buckled roads along the country's Pacific coast, killing hundreds of people .
President Rafael Correa said at least 233 people had died and rescuers were struggling to reach survivors trapped in the rubble.
The magnitude-7.8 quake, the strongest to hit Ecuador since 1979, was centred on the country's sparsely populated fishing ports and tourist beaches, 105 miles north-west of Quito, the capital.
Mr Correa reported the death toll on his official Twitter account while flying back from Rome to deal with the crisis. Officials earlier had reported more than 580 people were injured.
Vice president Jorge Glas said there were deaths in the cities of Manta, Portoviejo and Guayaquil - all several hundred miles from the centre of the quake which struck shortly after nightfall on Saturday.
In Pedernales, a town of 40,000 near the quake's epicentre, dozens of scared residents slept in the streets while men equipped with little more than car headlights tried to rescue survivors who could be heard trapped under rubble.
"We're trying to do the most we can, but there's almost nothing we can do," said Gabriel Alcivar, mayor of Pedernales.
Mr Alcivar pleaded for authorities to send earth-moving machines and emergency rescue workers to help find people amid the rubble. He said looting had broken out amid the chaos but authorities were too busy trying to save lives to re-establish order.
"This wasn't just a house that collapsed, it was an entire town," he said.
Mr Correa declared a national emergency and urged Ecuadoreans to stay strong while authorities handle the disaster.
"Everything can be rebuilt, but what can't be rebuilt are human lives, and that's the most painful," he said.
Mr Glas said 10,000 armed forces had been deployed to help. In addition, 4,600 national police were sent to the towns near the epicentre.
Officials said shelters had been set up and field hospitals were being deployed in Pedernales and Portoviejo.
More than 3,000 packages of food and nearly 8,000 sleeping kits were being delivered. Electricity in Manabi province, the hardest hit, remained mostly down as authorities focused on finding survivors.
"Compatriots: Unity, strength and prayer," Mr Glas told a throng of residents gathered in the streets of 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."
Homes were reduced to rubble along the quake's path, while in Guayaquil a shopping centre's roof fell down and a collapsed motorway overpass crushed a car. In Manta, the airport closed after the control tower collapsed, injuring an air traffic control worker and a security guard.
Alberto Reynas, 58, was fishing off the coast of Pedernales when giant waves violently rocked his boat.
"It felt the same on sea as it did on land," he said.
But he was shaken again when he returned to land to find the facade of his two-storey home had fallen off into the streets. He has been unable to communicate with members of his family and spent the night sleeping outdoors with neighbours, keeping a close watch against thieves.
"It's pure sadness. Everything is destroyed," he said.
Luis Quito said he spent the entire night delivering water to guests trapped under the rubble of the small, four-storey Hotel Chimborazo owned by his father-in-law, who was missing and he believed dead.
"We heard screaming all through the night," said Mr Quito. "There are humans trapped below the terrace. Babies. We need rescuers. But nobody has arrived so far."
In the capital Quito, terrified people fled into the streets as the quake shook their buildings. It knocked out electricity in several neighbourhoods and a few homes collapsed but after a few hours power was being restored.