West Midlands Police officers are investigating after a shop worker was attacked at the Esso garage on Lichfield Road, Shelfield, Walsall, on Saturday, October 20.
The victim, a man in his late 20s, saw a man filling his car with fuel at around 4.45pm.
Believing he was preparing to drive off without paying, the worker went over and challenged him.
The driver pulled an object from his back pocket, which he used to stab the member of staff in the arm and scrape his head.
He then got into his car and drove off without paying.
A spokesman for West Midlands Police said: “Police are investigating after a worker at Heath Service Station on Lichfield Road, Shelfield, Walsall, was stabbed in the arm by a customer.
“The victim suffered a small puncture wound to his arm and a scratch to the back of his head, and was treated in hospital.
“Anyone with information can contact us via Live Chat at west-midlands.police.uk between 8am to midnight, call 101 anytime or contact Crimestoppers anonymously on 0800 555111, giving crime reference 20WS/2420402A/18.”
A spokesman for West Midlands Ambulance Service confirmed paramedics were called to reports of an assault.
An ambulance and a paramedics area support officer were dispatched to the petrol station at 4.37pm.
A man was assessed before being taken to Walsall Manor Hospital for further treatment. He suffered minor injuries.