Wildfires are raging across the Pantanal tropical wetlands in southern Brazil, one of the most biodiversity areas in the world and a major tourist destination, regional authorities said on Thursday.
The governor's office in the state of Mato Grosso do Sul said the fires were bigger than anything seen before in the region.
So far, more than 50,000 hectares have been affected.
The blazes follow other wildfires that environmental groups say ravaged millions of hectares in the Amazon rainforest in August.
The statement from the governor's office said the situation was critical, with blazes ravaging three towns in the Pantanal, a popular eco-tourism spot.
Intense flames and reddish smoke have disrupted traffic on the highways, the statement said.
The coordinator of the National Risk Management Center, Paulo Barbosa de Souza, said the blaze - fed by wind and dry vegetation - was causing logistical difficulties.
Satellite images from the INPE space institute showed there were nearly 8,500 fires in the Pantanal area between January and October this year.
That was the worst record since 2007.