A South Australian police officer who took seven shots to put down an injured kangaroo has come under attack on social media.

Key points: A wildlife group called police to assist an injured kangaroo

A wildlife group called police to assist an injured kangaroo Rob Oswald posted footage of an officer's attempts to kill it

Rob Oswald posted footage of an officer's attempts to kill it Police say some animals are "more resilient than others"

SA Police said the officer was called to Stuart High School in Whyalla on Wednesday, after being contacted by a wildlife rescue group that a kangaroo had a broken leg.

A video of the ordeal was posted on Facebook by Rob Oswald, which on Thursday morning had been viewed almost 440,000 times and shared more than 6,000 times.

In the video, a police officer can be seen taking seven shots at a kangaroo just a few metres away, with the animal seemingly slow to react to the bullets and trying to stay on its feet.

Mr Oswald posted on Facebook that he had told the officer to use a rifle and criticised his attempts to euthanise the animal.

He described the incident as "cruel".

"If he didn't know what he was doing he shouldn't have done it," he wrote.

"He might as well have given me his gun, would have done a better job."

'Cruel' video receives backlash online

Footage of the incident sparked outrage on social media with many on Facebook labelling the officer's actions as animal cruelty and commenting about his ability to use the weapon.

"That's up there in animal cruelty. If you can't put down an animal in one shot, you have no business with a gun," Mark Bryant said in a Facebook comment.

"I'd hate to see this officer's response to a moving kangaroo … our understanding is the kangaroo was critically injured, so the officer wasn't trying to scare it off, he was just bad at trying to put it down," Nate Towers said in a post.

"And yet they claim hunters are cruel. This is ridiculous from the cop involved. Make the police actually get their gun license's instead of them doing a tiny bit of training than hand them a pistol," Tony Lever said in a post.

Police say 'some animals more resilient'

Police say officers have authority to kill injured animals. ( Supplied )

In a statement to the ABC, SA Police confirmed a number of attempts were made by the officer to "destroy" the kangaroo, but some animals could be more resilient than others.

A spokesperson said police had the authority to kill animals if they were injured.

"Police have the authority for the lawful destruction of birds or animals in circumstances where it is believed the bird or animal is in distress due to injury," a spokesperson said.

"In this situation this was the belief of the police officer after SAPOL were contacted by a wildlife rescue group that the kangaroo had a broken leg.

"A number of attempts were made by the officer to destroy the kangaroo, but each situation is different with some animals more resilient than others — even to bullets fired at close range.

"The kangaroo was destroyed by the officer.

"When any police officer uses their firearm a mandatory report must be submitted and the actions assessed.

"A final assessment has yet be completed on this incident."