Metropolitan police officers were called Wednesday around 7:40 p.m., local time (2:40 p.m. ET), following reports of a man shouting abuse at people on the street, according to a force statement Thursday.
The man reportedly injected food into three supermarkets on Fulham Palace Road in south-west London with multiple needles, police said.
He was arrested “on suspicion of contaminating goods with intent to cause public harm or anxiety,” the statement continued.
Affected supermarkets have been closed and crime scenes have been set, police said.
Anyone who bought food at the three affected supermarkets on Wednesday evening has been advised to throw it away as a precaution.
Police believe the processed meat and microwave products were affected.
“It is currently unknown as to how many items have been contaminated or with what,” the statement says.
“Investigations are underway to determine if there are other companies in the area involved in the incident.”
Environmental health experts work with the affected supermarkets, which police called Little Waitrose, Tesco Express and Sainsbury’s Local.