Officers were forced to shoot the “highly aggressive” dog, which survived and was recovering at home after surgery on Wednesday.

A woman was bailed up by the tan dog, believed to be a mastiff cross ridgeback, while in a dog park on Tuesday evening in Dunlop.

A man who went to the woman's aid was bitten, as was a 17-year-old boy who had his clothing ripped as the dog tried to bite him.

Acting Belconnen Station Sergeant Carolyn Uhe said police received three separate reports on the attacks before arriving on the scene shortly before 6pm.

She said an officer had lured the animal away from nearby members of the public before firing three shots.

“The dog was highly aggressive and actually confronted police,” she said.

“As a result, unfortunately the dog was shot by police.”

Sergeant Uhe said other options such as capsicum spray were considered by the officer before he discharged his weapon, but she said it was an appropriate response that did not risk any nearby members of the public.

“There was no risk at all,” she said.

“They were well away. The angle of the discharge was only two metres or so.”

Police have spoken with the owner, who cannot explain how the dog escaped the nearby backyard, and Territory and Municipal Services have taken over the investigation.

Director of city services Fleur Flanery said domestic animal services were working with the police, but they could not yet confirm if the animal would be destroyed.

“It’s not appropriate at the moment to take that dog,” she said.

Ms Flanery said staff had also assessed the dog, which does not have a history with domestic animal services, as well as its enclosure.

“We’ve done a fence inspection and there are some areas where we’ve asked the owner to improve the safety of the fence,” she said.

Ms Flanery said there were a range of infringements that could be issued in a similar situation, but nothing could be confirmed until the investigation was final. No expected date for its finalisation could be provided.

The incident has shocked Dunlop residents, one of which described the area as home to many young families.

“It’s certainly a one-off,” he said.

“This is a great area. Most people have little ‘pookie’ dogs. I don’t know where that dog came from.”

Another man told Fairfax Media he didn’t even hear any gunshots, despite being at home at the time of the incident.

An ACT Policing spokeswoman said the last incident involving such attacks was in 2010, when authorities were forced to destroy two dogs after a series of attacks.