Seven people in Germany have been taken to hospital, victims of a poisoning which turned their limbs blue.
The victims, a mix of students and staff, experienced nausea and some watched their arms or legs turn blue after using kitchen items and a drinks machine.
Police opened an attempted murder investigation after the incident at the Technical University Darmstadt.
Packets of milk and water containers were among the items spiked at the weekend with a chemical described as having a noticeably “pungent smell".
“For us, there is an initial suspicion of attempted murder in seven cases. This is based on the fact that a substance has now been detected in various food products which can be harmful to health and can even be fatal,” said Robert Hartmann, Darmstadt’s senior state prosecutor.
“We currently assume that this substance was deliberately introduced into the food products, hence investigating the suspicion of attempted murder.”
He said forensics officers had identified the poison but police in Darmstadt, near Frankfurt, were not releasing the information.
All six employees and students suffered medical problems on Monday and the incident appears to centre on one building, part of the Department of Materials and Geosciences, which has been cordoned off.
Police searched other university buildings as a precaution but found nothing linked to the suspected poisoning.
No one has come forward with symptoms from other buildings.
“We are shocked by the apparent offence that happened,” university president Tanja Bruehl said. “My sympathy is with those affected, who will receive full medical help.”
One of the victims was affected “relatively severely” by the poisoning but their life was apparently no longer in danger, Mr Hartmann said.
Police and prosecutors said they were trying to “identify the culprit or culprits” but there was no longer any “acute danger”.
Anyone feeling unwell or whose “extremities turn blue” should seek medical attention immediately, police said.
Germany has been shocked by several poisoning incidents in recent years.
In December 2019, five newborn babies were poisoned with morphine, but a nurse who was arrested was subsequently released.
A German court in 2019 sentenced Klaus O. to life in prison for spiking his colleagues' sandwiches with a poisonous powder containing lead, mercury and cadmium compounds. He was caught in 2018 trying to poison his colleagues.