A flood of toxic waste from a burst reservoir at a chemical plant has killed at least four people in Western Hungary.

As NPR's Eric Westervelt reports, local officials are scrambling to contain what they are calling "an ecological disaster."

Toxic sludge spilled into Kolontar, Devecser and Somlovasarhely. Several people are missing and there are more than 120 reported injuries.

Today Hungarian prime minister Viktor Orban said human error -- not flooding -- likely caused the spill. He added there was no threat of radiation from the contaminated sludge. But it is dangerous.

People are reporting burns and eye irritation. The national disaster unit says the sludge contains heavy metals, including lead. It is slightly radioactive and its dust can cause lung damage.

The disaster unit is pouring tons of plaster into the nearby Marcal river, to try to contain the spill.  Other efforts are underway to prevent the chemical sludge from getting into the larger Danube river.

According to The New York Times, "residents in Kolontar, not far from where the accident occurred, tried to rush from their homes as a 6-foot-high wave of sludge pushed its way through narrow streets and homes."

About 35.3 million cubic feet of sludge had leaked from the reservoir and was seeping into an area spread over 16 square miles, according to the Environmental Ministry.

In a statement on its website, MAL Magyar Aluminum said that the sludge contains iron oxide, aluminum, silicon dioxide, calcium oxide, and titanium dioxide.

The company claims it was not caused by human error.

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