Colombian rescuers are racing to find survivors as search operations enter a fourth day following Monday's magnitude 7.4 earthquake, the strongest quake to hit the country this century.

Authorities say at least 265 people have been killed and more than 3,500 injured, while nearly 500 people remain unaccounted for.

In Pereira, rescue teams are focusing on a collapsed bakery where they believe street vendor Pablo Loaiza may still be trapped. Specialist teams using vibration sensors and sniffer dogs have detected intermittent signs that someone could be alive beneath the concrete.

Relatives have gathered outside the site as rescuers work through the unstable rubble. Loaiza's 16-year-old niece, Sara Loaiza, said: “My heart is about to burst out of my chest.”

Rescue workers in Cali and Pereira are using cranes and hand tools to search damaged buildings, frequently calling for silence to listen for possible voices beneath the debris.

President Abelardo de la Espriella has declared an “economic emergency” and three days of national mourning following the disaster.

Thousands of people are sleeping outdoors in makeshift shelters, while volunteers are organizing food, water and blood donations for communities hit hardest by the earthquake.