A COVID-19 infected truck driver who failed to tell authorities he had visited Shepparton has been referred to Victoria Police.
The Department of Health and Human Services reported the matter and Victoria Police confirmed on Thursday morning it will assess whether any criminal offences were committed.
The development came as Victoria reported six new cases of coronavirus but no new fatalities, leaving the state's death toll at 816 and the national toll at 904.
Melbourne's rolling 14-day new case average has dropped to 8.9, and remains steady at 0.6 for regional areas.
Department of Health and Human Services figures also show the number of mystery cases in Melbourne rose by one to 15 for the period September 29 to October 12. There are no mystery cases in regional Victoria.
Shepparton residents overwhelmed testing sites on Thursday, after the new outbreak there sparked by the truck driver.
He didn't tell contact tracers he had been to the northern regional town.
The man, who was infected in the Chadstone Shopping Centre outbreak, visited Kilmore, Benalla and Shepparton while infectious on September 30.
The truckie, who had a worker's permit, admitted to illegally dining at a Kilmore cafe and visiting Benalla.
But he only told DHHS contact tracers he stopped in Shepparton after three people tested positive earlier this week.
Everyone in Shepparton has been asked to be tested for the virus.
Premier Daniel Andrews said there 1862 tests in Shepparton and nearby towns on Wednesday - usually the daily number had been around 60.
He added there were about 400 people isolating in the Shepparton community who are either outbreak cases, contacts or their contacts.
"They are isolated at home and they are isolated at home because of one person. That's the nature of this virus," he said.
DHHS testing boss Jereon Weimar said 350 Shepparton test results from Wednesday had all come back negative.
About 2000 tests had been done so far on Thursday.
One testing site at Shepparton Sports City had reached capacity soon after it opened at 10am on Thursday, but a second drive-through facility was due to open at that location from midday.
The Showgrounds test site also quickly reached capacity on Thursday morning.
Nine Australian Defence Force members were sent to Shepparton, along with Ballarat's rapid response team.
Mr Andrews apologised for the testing delays, but also defended the process.
"There's absolutely no notice provided here. That's the challenging part of it," he said.
"In less than 24 hours we have been able to stand up 11 test sites, if there needs to be 12, 13, 14 ... (but) there are limits on how quickly you can stand them up."
The three people who tested positive in Shepparton worked at Central Tyre Service on Welsford Street between September 30 and Tuesday.
Another five sites are also considered high-risk, with a further four listed as locations of concern.
Chief Health Officer Brett Sutton has "no doubt" the Shepparton community will get on top of the outbreak.
Meanwhile, police are investigating after Mr Andrews' electorate office was vandalised for the second time in less than a month.
His Noble Park office was cordoned off after "Sack Dan" was spray painted on the office and one of the windows cracked, apparently by a thrown brick.
