About 10,000 troops and 3,500 police officers were tonight being deployed in the affected areas, as rescue operations got under way.
The magnitude-7.8 quake struck on Saturday evening and was felt as far away as neighbouring Colombia.
Ecuador’s president Rafael Correa gave the latest death toll via his Twitter feed while flying back from a visit to Italy which he cut short to deal with the disaster.
He has declared a state of emergency and called on his country to be “calm and united”, after reports of unrest and looting in some areas.
The quake, the strongest to hit Ecuador since 1979, was centred on a sparsely populated area known for its fishing ports and tourist beaches, 105 miles north-west of Quito, the capital.
Vice-president Jorge Glas said there were deaths in the cities of Manta, Portoviejo and Guayaquil – all several hundred miles from the epicentre of the quake.
In Pedernales, a town of 40,000 people near the quake’s epicentre, dozens of scared residents slept in the streets while men using car headlights tried to rescue survivors 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 rescue workers as dozens of buildings in the town were flattened, trapping residents among 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 signed a decree declaring a national emergency and rushed home from a visit to Rome.
The country’s risk management agency said 10,000 members of the armed forces had been deployed to help. In addition, 3,500 national police officers were sent to the towns of Manabí, Esmeraldas and Guayas y Santa Elena; 500 firefighters were heading to Manabi and Pedernales and five shelters had been set up for those who had to leave their homes.
On social media, photos and videos circulated of homes reduced to rubble, a shopping centre’s roof torn apart, supermarket shelves shaking violently and a collapsed highway overpass that crushed a car. In Manta, the airport was closed after the control tower collapsed. An air traffic control worker and a security guard were injured.
In Quito, people fled into the streets as the quake shook buildings. It knocked out electricity in several neighbourhoods and six homes collapsed, but after a few hours, power was being restored, the 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 neighbours were screaming and kids crying.”
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 were shut down as a precautionary measure.