Seven people at a university in western Germany have received medical treatment after displaying symptoms of poisoning.
German police have begun an inquiry into suspicions of attempted murder following the incident at the Technical University in Darmstadt, south of Frankfurt.
The employees at the university experienced medical issues on Monday.
According to officers, milk cartons and water containers in one of the buildings on the campus appear to have been contaminated with a harmful substance between Monday and Friday.
The liquid was said to have had a powerful smell. Investigators have identified the substance, but due to the ongoing investigation prosecutors will not be publicly naming it.
Police and prosecutors said that other university buildings have been searched as a precaution, however nothing else was found linked to the suspected poisoning.
They also said that no other people have come forward with symptoms.
In a statement, police said they are doing everything to "identify the culprit or culprits". They added that as far as they are aware, there is no longer any "acute danger".
Prosecutor Robert Hartmann said they currently have no information pointing to anyone specific as a possible culprit - but authorities do believe the contamination may have been deliberate.
One of those affected was temporarily critical but their life apparently is no longer in danger, police said.
The university's president, Tanja Bruehl, said in a statement: "We are shocked by the apparent crime that took place at our university."