Port-au-Prince, Haiti (CNN) -- A strong aftershock rocked Haiti on Wednesday morning just as much-needed medical aid was set to reach the earthquake-ravaged nation.
The 6.1-magnitude aftershock was about 6.2 miles deep, with an epicenter about 35 miles (60 kilometers) west-southwest of the capital of Port-au-Prince, the U.S. Geological Survey said.
It rattled people struggling to recover from the devastating 7.0-magnitude earthquake that walloped the impoverished country January 12, killing at least 72,000 people.
Such a strong tremor can pose significant danger in a nation where damaged buildings are teetering precariously. The aftershock was the strongest to hit Haiti since last week's original quake, the USGS said.
The largest aftershock before Wednesday was magnitude 5.9, the agency said.