According to police, the blaze started in the Franklin Street cafe about 3.25am and caused smoke damage to neighbouring Westpac, Panthers Mensland and an antique shop on Seymour Street.

Traralgon Police Sergeant John Farquhar said the owner of Streeteats had been carrying out renovations in the cafe early this morning, before securing the building and leaving.

Sgt Farquhar said this was when the fire started.

Morwell CIU Detective Senior Constable Rod Findlay said the cause of the fire was not known and investigations were continuing.

Traralgon CFA incident controller Trevor Hair said firefighters contained the blaze in about 45 minutes and continued to monitor the building throughout the morning.

He said an aerial platform from Dandenong was called to help extinguish the blaze from above because structural damage made it dangerous to enter the building.

A section of Seymour Street and the footpath in front of the damaged building were closed off this morning.