A Waterloo Regional Police officer and two civilians involved in an altercation are all expected to survive, a spokesperson for Ontario’s Special Investigations Unit tells CTV News.

While the incident itself occurred early Thursday morning, police say it was the result of a chain of events which began Wednesday afternoon, when officers were called to a domestic disturbance.

Investigators say a couple were fighting inside the Morning Calm Drive townhouse, and police left after diffusing the situation.

Around midnight, the man returned.

According to John Ansell, who is leading the SIU probe into the case, the 30-year-old broke into the home and attacked the woman.

The two had recently broken up, Ansell said.

Police were called, and again made their way to Morning Calm Drive.

“During that encounter, the police officer was stabbed,” Ansell said.

“The officer responded with a firearm, and the man was shot.”

By this point, the noise had attracted the attention of neighbours, who were making their way out to the street to see what was going on.

“I just heard a scream. As I was coming out to leave, I heard a gunshot,” Alisha Melo told CTV News.

Another neighbour, Lori Ardiel, said she heard “a real big bang” and walked outside to see people laying on the ground.

After the exchange, Ansell said, police went inside and found a 30-year-old woman who had been stabbed multiple times.

All three injured people were taken to Cambridge Memorial Hospital.

The police officer was said to be doing OK. Ansell said she would likely be released from hospital Thursday.

The other two people were later transported to a Hamilton hospital to undergo surgery.

The man’s injuries were “potentially life-threatening,” Ansell said, but by later in the day all three were expected to survived.

A child inside the townhouse at the time was not injured.

“My understanding is (that) the child … is being looked after by Family and Children’s Services,” Waterloo Regional Police Staff Sgt. Mike Haffner told CTV News.

Neighbours say the woman who lives in the town house is a “quiet” and “friendly” single mother.

“She’s a good woman. She’s a good person,” said Naku Diaz.

“This is a complete shock.”

Homicide and domestic violence units of Waterloo Regional Police continue to investigate the altercation, as does the SIU.

Charges have yet to be laid.