At least 20 people were killed and dozens of buildings collapsed in cities across western Colombia on Monday after a powerful 7.4-magnitude earthquake struck the South American nation, trapping residents under debris, leaving more injured and forcing people to evacuate their homes as far as the capital of Bogota.The epicentre was in San Jose Del Palmar, a community of about 4,800 people in the Choco region about 250 miles (400 kilometres) west of Bogota, the US Geological Survey and Colombia’s counterpart reported. The USGS said it struck at a depth of 66 miles (107 kilometres). The quake also was felt in neighbouring Ecuador.Local officials confirmed that at least 18 people had been killed in the city of Pereira and two in the city of Manizales.