A police officer's head was repeatedly smashed into concrete in Melbourne when a group of thugs attacked him and a colleague as they tried to arrest a man over an alleged assault.
The officers were called to Fitzroy Street at St Kilda about 3am on Sunday after reports of an assault against a "vulnerable" woman.
While they were attempting to arrest a man they were outnumbered and allegedly attacked by a group.
"I would describe it as ragdolling him, smashing his head into the concrete roadway," Superintendent Tony Silva told reporters on Sunday.
"They were behaving like animals. They had that pack mentality," he said of the attack.
Despite the officers using pepper spray they were injured and both were taken to the Epworth Hospital.
One suffered facial injuries and the other will need surgery on his arm, the superintendent said.
"If they're going to behave like animals, that means being locked up like an animal, that's a matter for the justice system," Supt Silva said.
The attack horrified Victoria's Police Association president.
"I've seen a lot of things but watching this was one of the most horrific assaults on a police officer I've ever seen," Victorian Police Association president Wayne Gatt said.
A 26-year-old man is assisting police with their inquiries and they have urged anyone who may have witnessed the alleged assault to come forward.
© AAP 2019