A police dog being walked by his handler but two men in South Yorkshire.
The men, aged 19 and 44, were attacked in Lund Avenue, Barnsley, at around 5.15pm on Saturday.
An off-duty police officer was walking the dog when it struck.
A South Yorkshire Police spokeswoman said: “Two men, one aged 19, the other aged 44, both local to the area, suffered injuries in the incident - the 19-year-old to his leg, the other to his hand.
“Both received medical treatment for what are described as a minor leg injury and a more serious hand injury.
“An investigation into the circumstances of the incident has been launched by the force’s Professional Standards Department.”
Witnesses should call South Yorkshire Police on 101 quoting incident 886 of September 14.