Officials have declared a state of emergency in six of the country's 24 provinces and the National Guard. The tremor destroyed homes and collapsed one major overpass.
President Rafael Correa urged the country's 16 million people to remain calm during the crisis.
"Our infinite love to the families of the dead," he said on Twitter. He also announced that he would cut short his trip to Italy to return home.
Vice President Jorge Glas also announced that the number of injured people were not currently available but he admitted that the death toll is expected to rise.
"It's very important that Ecuadoreans remain calm during this emergency," Vice President Glas announced in a televised address.
"We're trying to do the most we can but there's almost nothing we can do," said Gabriel Alcivar, mayor of Pedernales near the epicentre.
He pleaded for rescuers as dozens of buildings in the town were flattened, people trapped and looting broke out amid the chaos. "This wasn't just a house that collapsed, it was an entire town."
On social media residents shared photos of homes collapsed, the roof of a shopping centre coming apart and supermarket shelves shaking violently. In Manta, the airport was closed after the control tower collapsed, injuring an air force official. Hydroelectric dams and oil pipelines in the OPEC-member nation were shut down as a precautionary measure.
Car flattened by collapsed overpass after 7.8 magnitude #earthquake in #Ecuador. pic.twitter.com/Zbw5QGI9Xa
— Scott McClellan (@bamasevere) April 17, 2016
Zoila Villena, a Quito resident said that she is in a current "state of panic."
"My building moved a lot and things fell to the floor," Villena told The Associated Press. "Lots of neighbors were screaming and kids crying."
That was the control tower Airport #Manta after earthquake in Ecuador pic.twitter.com/OzcUHnumvO
— Airplane Pictures ️ (@iLove_Aviation) April 17, 2016
The US Geological Survey said the shallow quake, the strongest since 1979 to hit Ecuador, was centred on south-southeast of Muisne, a sparsely populated area of fishing ports that is popular with tourists.
Additional reporting by AP
"We're trying to do the most we can but there's almost nothing we can do..."