An elderly man has been assaulted during a violent home invasion at Wanniassa in Canberra's south.

Police were called to the 83-year-old man's home on Embling Street at about 1:20am today, after another man broke in and demanded money, assaulting him in the process.

The break-in is one of three violent robberies in the ACT in the past week — although police said they did not believe the incidents were related.

The man hurt at in the Wanniassa incident was taken to hospital with head injuries, but has since been released.

ACT Policing's Detective Station Sergeant Matthew Reynolds said the man who broke in was Caucasian, between 35 and 45 years old, slim, about 180 centimetres tall and wearing dark clothes.

"This was an extremely cowardly and violent assault on a vulnerable member of our community and we're appealing for witnesses," he said.

Sergeant Reynolds said the elderly man was "absolutely shattered" by the attack.

"He's woken up in his house to find an offender in his house demanding money … it was a traumatic experience for him," he said.

More incidents at Watson, Civic

In an separate incident on Friday at about 10:40pm, several men entered a home on Molesworth Street in Watson and threatened the two people inside.

Both residents were assaulted and a firearm went off, but nobody was seriously hurt.

Detective Station Sergeant Matthew Reynolds said the 83-year-old was shaken badly by the attack. ( ABC News: Jana Black )

Last week, three men wearing balaclavas forced their way into an apartment at the Manhattan complex in Civic at about 9:50pm. A scuffle broke out, leaving a 31-year-old man resident with head injuries.

A woman in the apartment also suffered minor injuries, and the men made off with a small sum of cash.

Sergeant Reynolds said the injured man was hospitalised but had since been released.

He urged any residents in the complex with information who had not spoken to police to come forward.

"It is quite a brazen offence … that's why we're investigating and asking for information from anyone who may have seen anything," he said.

Witnesses or people with information on any of the break-ins were asked to contact Crime Stoppers.