(CNN)A man has been arrested on suspicion of contaminating food after processed meat and microwaveable products were injected with needles at three London stores.
Metropolitan Police officers were called at around 7.40 p.m. local time (2.40 p.m. ET) Wednesday following reports of a man shouting abuse at people in the street, according to a statement from the force Thursday.
The man reportedly injected foodstuffs at three supermarkets on Fulham Palace Road, southwest London, with a number of needles, police said.
He was arrested "on suspicion of contamination of goods with intention of causing public harm or anxiety," continued the statement.
The affected supermarkets have been closed and crime scenes are in place, said police.
Anyone who bought food from the three affected supermarkets on Wednesday evening has been advised to throw it away as a precaution.
Police believe that processed meat and microwaveable products were affected.
"It is currently unknown as to how many items have been contaminated, or what with," reads the statement.
"Investigations are on-going to establish if other businesses in the area are involved in the incident."
Environmental health experts are working with the affected supermarkets, which police named as Little Waitrose, Tesco Express and Sainsbury's Local.