A powerful earthquake shook western Colombia early on Monday morning, with reports of the tremors being felt in the capital Bogota and even far south across the border in Quito in Ecuador.

Officials said at least 18 people were killed in the town of Pereira. Rescue teams were working to free residents after buildings collapsed in Cali and other cities.

The epicenter was on the eastern tip of the Choco province on Colombia's Pacific coast.

What is the latest?

The mayor of Cali, Alejandro Eder, said that at least 20 buildings had collapsed, in some cases with people trapped inside.

"Residents of Cali, we currently have at least 20 collapsed structures in the city with people trapped inside; we are already managing this emergency alongside all of Cali's rescue agencies," Eder said on Instagram, posting an accompanying video statement. "I have requested support — specifically rescue personnel — from the mayors of Bogota and Medellin."

"We have just experienced a severe seismic event in the department of Choco. We are concerned about aftershocks," the governor of the Choco region, Nubia Carolina Cordoba-Curi, said online.

"Although the epicenter was in San Jose del Palmar, in the capital Quibdo there are injuries and severe damage to buildings. We are already conducting the damage assessment to issue the first official report," Cordoba-Curi said. Quibdo is home to around 150,000 people.

Colombia's civil aviation authority reported damage at six relatively minor airports and said flights were suspended while it was examined.

"Damage is reported at the airports of Pereira, Manizales, Quibdo, Armenia, Cartago, and Buenaventura. For safety reasons, air operations at these terminals remain suspended until structural damage to the infrastructure is assessed," it wrote online.

What do we know about the quake's size and location?

The US Geological Survey (USGS) initially measured the quake at magnitude 7.4. Colombia's national authority initially logged a smaller figure but later revised its reading up to 7.4 as well.

The epicenter was located just south of the Tatama National Nature Reserve, near Choco's eastern state border.

The epicenter was roughly equidistant from Colombia's three main cities, Bogota to its east, Medellin to its north and Cali to its south.

The closest major population center, Cartago, is home to about 140,000 people and around 30 kilometers (roughly 20 miles) from the quake's epicenter.

The USGS said the quake was also quite deep, striking around 107 kilometers below the ground. It estimated that most of the western half of Colombia would feel the tremors.

Tremors could also be felt in neighboring Ecuador to the south, and to the north and east in Panama and Venezuela.

USGS also recorded a fairly large aftershock, at magnitude 5.0, a little under an hour after the main quake.

The so-called Ring of Fire — the world's most active belt of tectonic plates and volcanoes encircling the Pacific Ocean — runs along Colombia's coastline not far from the epicenter of Monday's quake.

Edited by: Rebecca Staudenmaier

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