Workers in China killed more than 20,000 birds in a Shanghai live poultry market Friday morning after a sixth person died from the bird flu in Eastern China.
Fourteen people have now contracted the unusual strain of the virus, called H7N9 avian flu.
The virus had not previously been found in humans until a series of cases were reported in China this week.
The virus was found in live pigeons on sale in the Shanghai market, so workers slaughtered thousands of chickens, ducks, geese and pigeons. The market will be closed Saturday as workers disinfect the area.
Researchers in Japan and the CDC in the United States are working with the Chinese to track down the source of the virus, which does not appear to spread easily between humans.