Four men in balaclavas doused a Brisbane couple in their 60s with petrol and threatened to set them alight if they did not hand over money during an early morning home invasion on Sunday.

Police said the men, armed with a knife and a machete, broke down the front door of a house on Bridge Street at Wooloowin in Brisbane's inner-north about 2:40am.

They then poured petrol on the occupants - a 64-year old woman, who was awake and watching TV, and a 63-year-old man, who had been asleep - demanded money and threatened to set them on fire.

One of the offenders struck the woman, causing a laceration under her eye.

The couple's nephew, believed to be in his early 20s, was also home at the time of the incident but was unharmed.

Inspector Rob Graham said all of the home's occupants were left shaken by the attack.

"I spoke with the [man] that had been threatened, and he's understandably very shaken up," Inspector Graham said.

"He's trying to come to terms with what happened as well... he was in a deep sleep and when these four people came into the house.

"He said it happened so quick."

'Grubs' threatened people in 'their castle': police

Inspector Graham said the circumstances of the matter would be thoroughly investigated.

"There are certainly a number of lines of inquiries we are conducting at the moment to get to the bottom as to why these four grubs broke into this house and threatened these poor people," he said.

"Everybody's home is their castle and the last thing you expect at 2:40am is to have four grubs to come into your house, threaten you and steal your property."

The offenders were seen leaving the scene in two cars with a sum of jewellery and a purse containing coins.

One car was a silver-coloured SUV and the other was unknown.