Two men had to have surgery after an attack by a dog in Wanganui on Friday night - an attack so vicious that police could end it only by shooting the dog.
Acting Senior Sergeant Andrew McDonald said the men suffered severe bites in the attack.
Emergency services could do nothing until police shot the dog, which allowed them to get in and help the men.
The dog owner and another man were arguing in the driveway of a Bamber St house at around 7.30pm on Friday.
Mr McDonald said police were unsure why the man's dog - a large crossbreed - attacked them.