# The European Union has described Hungary's toxic spill as a serious environmental problem and has voiced concerns it could spread to other European countries along the river Danube ++ LM-REIN +++ At least four people were killed and 120 injured when toxic mud burst out of a reservoir at an aluminium plant near Kolontar on Tuesday. +++LM RAUS+++ Hungary has declared a state of emergency in three western counties and is battling to clear up after the spill.