After several people at the Technical University of Darmstadt showed signs of poisoning, investigations have shown that there was a harmful substance in several milk cartons and water containers.
The South Hesse police wrote that on Monday evening on Twitter.
The police suspect that the substance caused the symptoms of poisoning.
The police said in the evening which substance it is still has to be investigated.
According to the current status, the containers were mixed with the substance over the course of the past weekend.
Six people had to be cared for in a hospital on Monday.
All had previously eaten or drunk something in building L201 on the Lichtwiese campus, said a police spokesman.
For one person, the situation was temporarily critical, but was stable again.
The officials advise everyone who has had a drink or a meal in building L201 on the Lichtwiese campus on Monday and feels unwell or has bluish discoloration of the extremities to seek medical treatment immediately.
In the event of discoloration, one should not move as much as possible and call the emergency doctor immediately.
The people in Hesse who ate at TU Darmstadt were also warned via the Katwarn app.
As a precaution, emergency services wanted to search other buildings on campus for "contaminated products" in the evening.
By early evening, no other people reported feeling unwell or with symptoms of poisoning.
The investigators' focus had been on a "kind of tea kitchen" in which items would also be stored - for example in a refrigerator.
These rooms are freely accessible.
kfr / dpa
