Warrnambool police have collected samples for forensic testing after a fire in an apartment above a Liebig Street restaurant.

Detective Senior Constable Josh Walters, of the Warrnambool police crime investigation unit, said the samples would be tested after a bin fire in the flat on Friday morning, April 12.

It's understood there is a tenant in the apartment above the Zambrero restaurant was not at home after emergency services were called out to a fire in the unit at 6.44am.

Police and firefighters attended and the fire was quickly contained.

"No one was home when police arrived," Detective Senior Constable Walters said.

There have been no arrests and investigations are continuing.

It's understood the apartment has been damaged by smoke, which was seen billowing out of the flat.

Anyone with information is requested to contact the Warrnambool police CIU on 5560 1156 or Crime Stoppers on 1800 333 000.

At 8.09am:

Warrnambool police detectives are investigating the circumstances surrounding an emergency call-out to a Liebig Street flat early Friday morning, April 12.

A police spokesman said the emergency call was to a home at the top of the Zambrero restaurant.

A Fire Rescue Victoria spokesperson requested that all inquiries be referred to the Warrnambool police crime investigation unit.

Earlier: Four Warrnambool fire trucks have converged on the city's main street after a call-out at 6.44am Friday.

Fire Rescue Victoria officers seem to be centering their attention on the roof-top rear section of shops.

The emergency was listed as under control at 7am.

Three trucks were parked in Liebig Street while another was in the Ozone car park at the rear of the shops.

There is no sign of smoke.

More to come.