Rescue workers work to pull out survivors trapped in a collapsed building after a huge earthquake struck, in the city of Manta early on April 17, 2016. Ariel Ochoa/AFP/Getty Images

UPDATE: 3:13 a.m. EDT — At least 77 people were killed and 500 were injured after a magnitude-7.8 earthquake hit Ecuador Saturday. A state of emergency was declared in six provinces, and the National Guard has been mobilized.

The revised death toll was reported by Vice President Jorge Glas, according to BBC, and he added that 588 people had been injured so far. He also said that the number could increase as many affected areas had not been reached. The earthquake is the largest in the country in decades. The quake, with a depth of 12.4 miles, was followed by 55 aftershocks.

A resident of Manta Ramon Solorzano told Reuters: "Most people are out in the streets with backpacks on, heading for higher ground,” adding: “The streets are cracked. The power is out, and phones are down.”

UPDATE: 12:54 a.m. EDT — Ecuador's Vice President Jorge Glas said the earthquake death toll was now at 41 and was expected to rise.

UPDATE: 11:46 p.m. EDT — Ecuador has declared a state of emergency in six provinces and mobilized its national guard following Saturday's earthquake, the BBC reported.

Meanwhile, the government of the Galapagos Islands, due west of Ecuador, has advised caution in coastal areas amid reports of strong waves but has not called for evacuations.

At a news conference, Ecuadorian Vice President Jorge Glas said 16 people had been killed in Portoviejo, 10 in Manta and two in Guayas province.

Provinces where a state of emergency was declared were Esmeraldas, Los Rios, Manabi, Santa Elena, Guayas and Santo Domingo, the BBC reported.

People stand next to the debris of a building in Manta, Ecuador, after a magnitude-7.8 earthquake struck off the country's northwest Pacific coast, causing "considerable damage," April 16, 2016. Patricio Ramos/Reuters

UPDATE: 11:29 p.m. EDT — As a precaution following Saturday's earthquake, Ecuador has halted production at the nation's 110,000-barrel-per-day oil refinery in Esmeraldas, Reuters reported in an alert.

UPDATE: 11:12 p.m. EDT — Concerned about rising tides following Saturday's deadly earthquake, Ecuador's government recommended that residents leave coastal areas, Reuters reported.

Meanwhile, photos posted to social media showed what were described as heavily damaged buildings in Portoviejo and Guayaquil. Other photos showed damage in Manta and in Quito, the nation's capital.

UPDATE: 11:03 p.m. EDT — Juan Manuel Santos, president of neighboring Colombia, tweeted a message of solidarity with the people of Ecuador and President Rafael Correa following Saturday's deadly magnitude-7.8 earthquake:

UPDATE: 10:44 p.m. EDT — At least 28 people have been killed by Saturday's earthquake and aftershocks in Ecuador, Vice President Jorge Glas said, according to a Reuters alert. Sixteen were said to have been killed in Portoviejo. One death was reported earlier in a bridge collapse in Guayaquil.

UPDATE: 10:34 p.m. EDT — Government officials in Ecuador said Saturday's earthquake had caused "considerable damage" in areas near the epicenter and in the commercial area of Guayaquil, Reuters reported.

UPDATE: 10:26 p.m. EDT — Police in Guayaquil, Ecuador, recovered a body Saturday at the scene of a bridge collapse following a magnitude-7.8 earthquake, CNN reported. It was the only death immediately linked to the quake.

UPDATE: 10:19 p.m. EDT — Some parts of Quito, the capital of Ecuador, lost electric power or telephone service following Saturday's magnitude-7.8 earthquake, Reuters reported. But service was later restored, and there were no reports of casualties in the city.

Photos of damage, supplied by Ecuador's government, showed that a bridge had collapsed in Guayaquil and an airport tower had collapsed in Manta, Reuters reported.

Meanwhile, Facebook activated its Safety Check feature following the quake.

UPDATE: 9:58 p.m. EDT — No changes in sea level have been reported along Ecuador's coast, where a magnitude-7.8 earthquake occurred Saturday, the Ecuador navy's National Oceanographic Institute reported via Facebook.

UPDATE: 9:50 p.m. EDT — Several aftershocks of magnitude-4 and -5 have been reported along Ecuador's coast following Saturday's magnitude-7.8 earthquake, Ecuador's Instituto Geofisico reported.

UPDATE: 9:35 p.m. EDT — Video posted by the Los Angeles Times shows shoppers reacting to Saturday's earthquake in Ecuador:

UPDATE: 9:30 p.m. EDT — DGAC, the aviation authority in Ecuador, reported that Eloy Alfaro International Airport in Manta has been closed because of Saturday's earthquake.

UPDATE: 9:20 p.m. EDT — Saturday's earthquake along Ecuador's central coast was felt as far away as Quito, the South American nation's capital, about 107 miles from the quake's epicenter, the Los Angeles Times reported. People reportedly fled shaking buildings and gathered in the streets.

The quake struck at 4:58 p.m. PDT, the Times reported.

UPDATE: 9:10 p.m. EDT — The U.S. Geological Survey has upgraded the Ecuador earthquake to magnitude 7.8 and says it struck at a depth of 19.2 kilometers (11.9 miles).

Original story:

An earthquake with a preliminary magnitude of 7.4 occurred Saturday night in Ecuador, the U.S. Geological Survey reported. The epicenter was about 17 miles south-southeast of Muisne, the USGS said.

A collapsed road was spotted in Guayaquil, an Ecuadorean television station reported.

Other local media reported power outages and structural damage on land in the affected area, and government authorities warned that tsunami waves were possible for Colombia, Costa Rica, Panama and Peru.

This is a developing story. Check here for updates.