Devecser , Hungary ( CNN ) -- The Hungarian government Thursday made an urgent request to the European Union for help in the cleanup effort after a reservoir holding industrial waste burst earlier in the week . The government wants expert assistance in three villages left covered by the toxic red sludge after the accident Monday , the official news agency MTI reported . Meanwhile , the sludge from an aluminum plant reached the Danube , Europe 's second largest river , on Thursday as emergency officials worked to contain as much of the leak as possible . `` It is a huge tragedy for the whole country , '' said Anna Nagy , a Hungarian Disaster Management offical . `` We love the Danube , we 're very proud of the Danube and we tried to protect it . '' `` I hope we can save the life in the river , '' she said . Hungary needs time to calculate the cost of the disaster , saying that the government 's first response had been to try to save lives and clean homes . Tibor Dobson , a top disaster management official , told CNN that the sludge -- which flowed from an aluminum plant reservoir that burst on Monday -- is less dangerous than it was when it spilled . Officials believe pH levels have dropped to within an acceptable range , making the river safe , Dobson said . They are monitoring the Danube for sign of toxicity , such as dying fish . Nagy said pH levels had fallen to 9.1 . That 's more alkaline than neutral , which is 7 on the scale , but much less than it was originally , at 13 , the Catastrophic Protection Unit said Thursday . Emergency workers were pouring plaster and fertilizers in hopes it would bind with the sludge and counter its alkalinity . The exact chemical composition of the sludge has not been revealed , but aluminum processing normally involves compounds that include cyanide , cadmium and chromium . The environmental disaster -- which occurred nearly 100 miles west of Budapest near the town of Ajka -- has killed two children , ages 1 and 3 , an elderly woman and a 35-year-old man whose SUV overturned in the sludge . About 250 people have been evacuated from their homes , said Gyorgi Tottos , a spokeswoman for Hungary 's Catastrophe Protection Unit . The reservoir has since been repaired and the flow from the pool halted . But the material that flowed out of the reservoir continues to pose a threat . The plant received an operating permit in 2006 , he said . The European Commission is studying a copy of the permit and sees nothing wrong with the paperwork so far , he added . The aluminum factory has said it will pay for the victims ' funerals . It has property and liability insurance , insurer Allianz Hungaria Biztosito told CNN , but would not say how much . Residents were advised not to eat produce from gardens that were covered when the dam burst . It was not clear when residents evacuated from affected areas in the villages of Kolontar , Devecser and Somlovasarhely would be able to return home . The long-term consequences of the leak were also unclear . In some villages , police with guns patrolled some of the villages to keep looters at bay . A state of emergency has been declared in three counties , the State Secretariat of Governmental Communications said . CNN 's Nic Robertson , Tommy Evans , Jim Boulden and Eileen Hsieh contributed to this report .
Hungary asks European Union for help in response . ` ` It is a huge tragedy for the whole country , '' a Hungarian official said . Officials think the pH level has dropped , but is still above neutral . The sludge came from a aluminum water pipe that burst on Monday .