A state of emergency has been declared in three regions in the west of Hungary after toxic sludge from an aluminium smelting plant flooded the area.
Troops in protective gear have been helping to clean up the spill, thought to come from an overflowing reservoir after weeks of heavy rain.
Up to 700 thousand cubic metres of the red sediment escaped from the plant 160 kilometres from the capital, Budapest.
At least three people are known to have died and scores have been injured – most of them have chemical burns.
Doctors are warning the burns could take days to appear.
110 people were rescued from the flood. A further 390 have been given emergency shelter.
Hungary’s Environment Minister says this is the worst chemical accident in the country’s history.
The fear is the sludge could reach the Raba and Danube rivers.