Neighbours and fire crews rushed to the scene on Lambrigg Street just after 11pm to find several cars, as well as parts of a house, alight.

Farrer local Heather Wilkins ran across the road to help neighbours battling the flames after hearing the sound of a "car screeching".

"We thought a car had crashed so we headed over and saw it was actually the cars in the garage that were on fire," Ms Wilkins said.

"By the time I got out the front gate, most of the cars were completely engulfed...

"It got very hot very quickly. It was quite dramatic."

ACT Fire and Rescue crews arrived within minutes to extinguish the blaze, but not before it had caused significant damage.

On Sunday morning, police said they believed the fire was deliberately lit and had deemed it suspicious.

Ms Wilkins said both the house and garage were "quite burnt out".

"It seemed to take them forever to put [the fires] out, there was foam flowing down the street," she said.

"The elderly neighbour next door was trying to hose [the garage] down over the fence, so I got him safely away.

"I don't think the family were home at the time."

Ms Wilkins had been celebrating her fiance's birthday with friends and family when the fire started.

"We were toasting marshmallows and having a lovely night," she said. "It was quite a brazen time for it to happen...everyone was around."

The usually "quiet street" is home to mostly families and elderly people, Ms Wilkins said.

"We've got one neighbour who is in their 90s and others are in their 80s, so it was a bit much for them at 11 o'clock at night," she said.

"But we got everyone cleared out safe and I don't think anyone was injured thankfully."

Anyone with information about the fire is urged to contact Crime Stoppers on 1800 333 000, quoting reference number 6118136.