France ordered a large-scale killing of ducks on Wednesday in three areas where a severe bird flu outbreak is currently underway, according to a Reuters report.

The country’s agriculture ministry said the highly contagious H5N8 bird flu virus has spread quickly through poultry populations in southwestern France, with 89 cases reported in total so far. So the ministry ordered that the free range ducks and geese in the administrative departments of Gers, Hautes-Pyrenees and Landes be culled in response — with an estimated total of 800,000 in the next week, Reuters reports.

“The principle is to quickly kill the species most affected to date by the virus,” the ministry said in a statement, according to Reuters. The statement added that the ducks to be killed were owned by foie gras producers.

Marie-Pierre Pe from foie gras-maker CIFOG told Reuters that the number of ducks killed could continue to increase if authorities fail to stem the spread of the virus. The ministry gave a deadline of Jan. 20 for the culling, but an official said they could stop earlier if the outbreak is contained.

Both the Czech Republic and Slovenia announced the first outbreaks of this bird flu strain Wednesday.

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Write to Julia Zorthian at julia.zorthian@time.com.