Hopes were fading Monday of finding survivors more than four days after powerful twin earthquakes struck Venezuela, as residents grow increasingly frustrated with the government’s response to the disaster that has killed at least 1,450 people and left tens of thousands unaccounted for.

A strong aftershock was felt in the hardest-hit areas of the capital Caracas and La Guaira shortly after 7:00 am (1100 GMT) on Monday, which the US Geological Survey measured at magnitude 4.6, adding to fears for the safety of hundreds of buildings weakened by the tremors.

French and American rescue teams found a man and his teen son alive under the rubble on Sunday in Caraballeda, a town about 40 kilometers (25 miles) north of Caracas, AFP journalists saw.

The rescue offered a glimmer of hope in an ongoing tragedy that has shaken a country already mired in an economic crisis, but that hope dwindled as the critical 72-hour window for rescuing trapped victims passed.

Millions more people were feared to lack sanitation and other basic needs after one of Latin America’s most devastating earthquake disasters.