Police are appealing for information after a 40-year-old man is believed to have been jabbed in the leg with a needle in Halifax.
Investigations into the incident are currently ongoing and police are appealing to anyone who witnessed the incident or who has any information to contact them.
The incident is said to have taken place half way along Park Road, at the bottom of People's Park, at 9.40am.
Police are keen to trace a man who is described as being Asian and in his late 20s to early 30s. He is said to be 5ft 10ins tall and of medium build, with black hair, shaved very close at the sides and spiky on top. He was wearing a black coat and jeans.
DCI Terry Long, of Calderdale Police, said: "Police are investigating a totally unprovoked attack on a public service worker going about his daily business. We are appealing to anyone with any information to contact us."
Anyone who witnessed the incident or who has any information is urged to contact PC Emma Leatherland in Calderdale Police on 0845 6060606 or Crimestoppers, anonymously, on 0800 555111.