A powerful 7.8 magnitude earthquake in Ecuador has killed at least 77 people and injured more than 500, Vice President Jorge Glas says.
The quake struck just before 7pm on Saturday (local time) near the northern coastal town of Muisne.
Widespread severe damage is reported, with a bridge destroyed as far south as Guayaquil about 300 kilometres away.
President Rafael Correa, who is flying back from a trip to Italy, has decreed a state of emergency.
He said: "This is a very painful test. I ask the country to be calm and united... Let's be strong; we will overcome this."
He added: "Roads and hospitals can be rebuilt; you cannot recover lost lives. That's what hurts the most."
The quake, the country's largest since 1979, also shook buildings in the capital, Quito.
Mr Glas said that at least 77 people had died and 588 had been injured, adding that the figures could rise as a number of affected areas had not yet been reached.
He called for calm, particularly in the city of Portoviejo, amid reports of a "lack of public order", and said that 10,000 troops and 3,500 police had been mobilised for the affected areas.
Authorities urged people to evacuate coastal areas for fear of rising tides.
Gabriel Alcivar, mayor of the town of Pedernale, which is close to the epicentre, said: "We're trying to do the most we can but there's almost nothing we can do."
Dozens of buildings had been flattened and looting had broken out, he said.
"This wasn't just a house that collapsed, it was an entire town."
Carla Peralto, a resident of Boyaca, one of the worst-affected areas, said: "I never felt something like that in my life. It was so strong. I was feeling very, very scared... I was thinking 'God, please stop that because maybe I die today'."
Serious damage was also reported in the city of Manta, with an airport tower among the buildings destroyed.
Manta resident Ramon Solorzano said: "Most people are out in the streets with backpacks on, heading for higher ground. The streets are cracked. The power is out and phones are down."
The US Geological Survey said the earthquake struck at a fairly shallow depth of 19.2km, about 27km from Muisne in a sparsely populated area.
Guayaquil Mayor Jaime Nebot, who was travelling in Spain, said on his Facebook page he would coordinate recovery operations from where he was.
Official details on the damage to Guayaquil, a frequent departure point for foreign tourists visiting the Galapagos islands made famous by Charles Darwin, were slow to emerge.
Social media pictures showed a collapsed bridge in the city and minor damage to the lobby of a hotel.
"I was in my house watching a movie and everything started to shake. I ran out into the street and now I don't know what's going to happen," said Lorena Cazares, 36, a telecommunications worker in Quito.
Parts of the capital were without power or telephone service, with many communicating only via WhatsApp. Photos on social media showed cracks in the walls of shopping centres.
The capital's municipal government later said power had been restored and there were no reports of casualties in the city.
The Pacific Tsunami Warning Center said tsunami waves reaching 0.3 to one meter (one to three feet) above tide level were possible for some coastal areas of Ecuador.
State officials said the OPEC nation's oil production was not affected by the quake but that the principal refinery of Esmeraldas, located near the epicentre, had been halted as a precaution.
"At first it was light, but it lasted a long time and got stronger," said Maria Jaramillo, 36, a resident of Guayaquil, describing windows breaking and pieces falling off roofs.
"I was on the seventh floor and the light went off in the whole sector, and we evacuated. People were very anxious in the street ... We left barefoot."
Across the Pacific in Japan, a 7.3 magnitude tremor struck Kumamoto province early Saturday, killing at least 32 people, injuring about a thousand and causing widespread damage in the second major quake to hit the island of Kyushu in just over 24 hours. The first, late on Thursday, killed nine.
The Ministry of Civil Defence said there was no threat of a tsunami reaching New Zealand as a result of the earthquake.
The Ministry of Foreign Affairs said there was no information to suggest there were any New Zealand casualties in the earthquake.
There are currently 29 New Zealanders registered on its safetravel website as being in Ecuador, but authorities there have been in contact to say there are no New Zealand casualties.
The ministry is advising New Zealanders in the affected area to contact their families to let them know they are safe.
- Reuters / RNZ / BBC