People stand on the debris of a building after an earthquake struck off the Pacific coast in Manta, Ecuador, April 16, 2016.[Photo/Agencies]

GUAYAQUIL - A powerful earthquake killed at least 77 people, injured hundreds more, ravaged coastal towns and sent residents fleeing for higher ground in Ecuador on Saturday night.

The 7.8 magnitude earthquake struck off Ecuador's Pacific coast and was felt hundreds of miles (km) away in the capital of Quito as well as in the large commercial city of Guayaquil, where rubble lay strewn in the streets and some buildings were cracked or partially collapsed.

A bridge in the city collapsed on top of car, crushing it.

The earthquake was Ecuador's worst in decades and officials said the death toll was likely to rise even higher as rescue teams headed into the hardest-hit areas.

"It was terrifying, we were all scared and we're still out in the streets because we're worried about aftershocks," said Guayaquil security guard Fernando Garcia. "Everything is damaged."

A state of emergency was declared in six provinces.