German police said on Tuesday that they had launched an investigation after bottles of drinks containing a deadly poison were found in two Munich supermarkets.
The poison was found in the two locations in four separate incidents, and in three of the four, customers consumed small amounts of the toxic liquid, police said.
Two women aged 34 and 42 had to receive immediate medical attention after drinking the beverages.
The third, a 48-year-old, suffered from symptoms including dizziness and nausea, but did not require medical attention.
The fourth bottle found to contain poison had not been sold yet, they said.
Police are yet to determined the motive for the crimes, and a police spokesman said that blackmail was unlikely because the supermarkets had received no demands until this point.
They advised the public to be aware of any unusual smells coming from beverages, and to inform them immediately should the substance be suspicious in any way.