The fire broke at the caravan park on McKenzie Road just after 11.30 pm on Monday night. There were people in another parts of the park, but not in the affected units.
Eight CFA trucks from seven brigades attended: Mansfield, Bonnie Doon, Goughs Bay-Howes Creek, Maindample, Booroolite & District, Glenroy/Merrijig and Jamieson.
District 23 Commander Trevor Ebbels said the fire measured 100 by 20 metres and was kept to one block of the caravan park.
"The brigades did really well to stop it where they did," he said.
A number of trees were impacted and are being assessed for safety.
A fire investigation is currently underway to determine the cause of the fire.