Officers were called to the Esso garage in Nuthall Road, Whitemoor, Nottingham, at around 5.45am this morning (2 April).
The victim, a man in his 20s, had entered the garage shop after suffering serious injuries.
He remains in the hospital with injuries which are not currently believed to be life-threatening.
Detective Sergeant James Hirst, of Nottinghamshire Police, said: “This was a violent assault that left a young man in hospital.
“We are currently investigating what happened in the moments before, during and after this incident and urge any potential witnesses to come forward.
“Even at this time of the morning on a Sunday, this is a busy road and we believe there may be motorists with dash-cam footage which could help with our investigation.
“There will be a large police presence in the area today while we carry out inquiries but we currently believe this to have been an isolated incident with no wider risk to the public.
“If anyone has concerns, I would encourage them to speak to an officer.”
