Dozens of intruders left a trail of destruction when they broke into the empty Shaw Place home on Tuesday night after a 'free house' party was advertised on Facebook.

Police said almost 70 young people aged between 15 and 18 fled in cars parked in the street when they arrived, following reports of people in the house shortly after 9pm.

The teenagers smashed windows, tore holes infreshly painted gyprock, ripped doors from their hinges, slashed curtains and pulled hanging lights from the ceiling.

Tomato sauce was sprayed on the walls and the vandals had tossed empty beer bottles and bourbon cans throughout the house and garden.

The young couple, who bought the house recently and were given the keys last Tuesday, were in shock as they examined the damage on Wednesday morning.

The first home buyers had yet to settle on the home but had been given early access to patch the walls and paint the interior.

"What have we done to deserve this?" one owner said.

The woman had called police after she arrived at the house to find a side gate, laundry door and front door open on Tuesday afternoon.

They arrived to find seven police cars at the property.

"We knew then it was bad," the woman said.

"The police brought us in and said 'it's pretty much the worst we've ever seen, so be prepared'.

"We had to sit in the car for a few hours to wait for the police forensics team and we just sat there and didn't say anything.

"What can you do? There's nothing we can do."

The pair had hoped to move in by the end of next week.

Loss adjuster Daniel Kim, who inspected the home on Wednesday, estimated the damage at $100,000.

"The amount of damage I've seen today is just phenomenal,” Mr Kim said.

"I've never seen a house with this much damage from one incident."

The house was fully insured.

One neighbour said cars full of young people had started to pull up in the quiet cul-de-sac about 8.30pm on Tuesday.

About half an hour before, a car had pulled up further down the street for a few minutes.

There were banging noises shortly after 9pm, before the young people were heard to run back to their cars and drive off, the neighbour said.

Another nearby resident told the couple he had heard smashing glass but ignored it because he knew the house was being renovated.

Acting officer-in-charge of the Tuggeranong police station, Sergeant Mark Rowswell, said the incident was a wanton display of senseless vandalism, with little regard for the homeowners.

"At this time we have a number of vehicle registrations of fleeing cars, which we will be following up on," he said.

"For any teens that were involved, I urge you to come forward and talk to us."

Any information to Crime Stoppers, 1800 333 000.