Hungary opened a criminal probe into the toxic sludge flood Wednesday and the European Union urged emergency authorities to do everything they can to keep the contaminated slurry from reaching the Danube and affecting half a dozen other nations.
Hundreds of people had to be evacuated after a gigantic sludge reservoir burst Monday at a metals plant in Ajka, a town 100 miles (160 kilometers) southwest of Budapest, the capital.
At least four people were killed, three are still missing and 120 were injured as the unstoppable torrent inundated homes, swept cars off roads and disgorged an estimated 1 million cubic meters (35 million cubic feet) of toxic waste onto several nearby towns.