Czech police say they have discovered two possible sources of methanol poisoning that has killed at least 18 people.

About 400 liters (106 gallons) of illegal alcohol was seized and two male suspects arrested in the northeastern part of the country where most victims lived. Around 500 bottles and several barrels of illicit booze have been found in a garage in the eastern city of Zlin on Thursday. Methanol tests still have to be conducted.

Health Minister Leos Heger said Thursday a majority of alcohol samples taken elsewhere that have been tested so far contained dangerous levels of methanol that is mainly used for industrial purposes.

About two dozen people are hospitalized, some in critical condition after drinking vodka and rum laced with methanol.