Detective Sergeant Jason von Tunk, of the Portland police crime investigation unit, said the aggravated burglary happened soon after 9pm on Saturday at a Waratah Crescent address.

"Three people wearing masks and armed with baseball bats have entered the home and demanded money," he said.

"The victim and his mother were home at the time. There were threats but no one was injured.

"The offenders then stole property and left. The victim's mother called triple zero at 9.15pm."

Sergeant von Tunk said detectives were still in the early stages of the investigation and requested anyone with information contact the the Portland police station or Crime Stoppers on 1800 333 000. 

In Warrnambool, $5000 in cash and a slug gun was stolen from a gun safe between 2pm and 10pm on Friday.

Detective Senior Constable Craig Wastell, of the Warrnambool police crime investigation unit, said an offender or offenders entered the Pecten Avenue home while the residents were away.

"They have returned and found the $5000 and a slug gun missing," he said.

"The woman had sold her car and was storing the cash in the gun safe, but the offenders found the key and opened the safe. 

"Fortunately a high-powered rifle usually in the gun safe is no longer stored there."

Detective Senior Constable Wastell said crime scene officers would attend the home in the search for forensic evidence.