The 7.4-magnitude earthquake tore through Colombia's coffee-growing heartland early on Monday, killing at least 164 people.
The quake reduced multi-storey buildings to rubble in cities such as Pereira and Cali, and cracked apart one of the towers of a historical cathedral in the city of Manizales.
Emergency teams aided by police, soldiers and volunteers worked through the night with excavators and, at times, their bare hands, hunting for survivors beneath debris.
In Cali, home to about 2.2 million people, at least 85 people were killed, with dozens of buildings left leaning precariously or destroyed outright, forcing residents into the streets.
Several of the top floors of one of the city's hospitals - some dedicated to pediatric care - collapsed upon themselves, leaving some patients trapped and forcing some 600 others to be tended to on a street strewn with rubble, hospital director Irne Torres Castro told Caracol television.
Carmen Yasmin Garcia, 43, a Cali resident volunteering with rescue teams, said on Monday afternoon that her group had freed seven people from a collapsed building, but four others and a dog remained trapped.
"A moment ago there was scratching but now we can't hear anything, we still have faith that the dog is alive and we can get these people out," Garcia said.
"We need people with sticks and spades, the more people lending a hand the better."
In Pereira, capital of the hard-hit state of Risaralda, authorities reported 66 dead.
The city also bore some of the most visible destruction, with entire residential blocks reduced to piles of concrete and twisted steel.
Video posted on social media and verified by Reuters showed the city's airport violently swaying during the quake, with large chunks of the ceiling collapsing as people sheltered.
Another 13 people died in Choco, the rural province closest to the quake's epicentre.
President Abelardo De La Espriella, who assumed power just days ago, said 35 people died in Cali alone, while 188 were missing.
He said 1000 members of the security forces would be deployed to the city by dawn following reports of looting.
Cali, as well as Pereira, implemented curfews on Monday night.
"Our intention is to co-operate in any way necessary. Here, there are no distinctions or ideological divisions when it comes to defending our people or showing solidarity," De La Espriella told journalists on Monday evening.
The disaster has drawn comparisons to a deadly 1999 earthquake that devastated the same coffee-growing region, killing more than 1000 people, as well as to catastrophic quakes that killed more than 6300 in neighbouring Venezuela in June.
