Police probe 'horrifying' home invasion, extortion plot

Investigators have escalated their search for four armed thieves accused of forcing entry into a home and attempting to extort its occupants.

Four balaclava-clad offenders are alleged to have forced entry to a Keilor Downs home, in Melbourne's northwest, about 2am on Monday, April 20.

Three occupants - a 62-year-old man, 54-year-old woman and 17-year-old girl - were inside at the time.

The offenders, believed to have been armed with firearms and a sledgehammer, forced the trio into a room and covered them with blankets, Victoria Police allege.

They then allegedly plundered the home and threatened to return if a large sum of cash was not paid by a deadline.

The occupants were not physically injured during the ordeal, which lasted about two hours, with the offenders only leaving shortly after 4am.

On Monday, police released digital composite images of two men they believe can assist with their enquiries along with CCTV of a vehicle of interest.

"We're adamant there are people out there that will know the identity of the two people we've released images of today," Detective Sergeant Jason Connor said.

"We're conducting a thorough investigation of this violent incident, and it won't be long until we come knocking on doors and making arrests."

Police believe the "horrifying" incident was targeted and that the stolen property has not been returned.