The Red Cross says 12 emergency relief centres have been inundated with people forced to flee their homes and more are still arriving.

Up to 100 people registered at the centres overnight.

Red Cross State Emergency Manager Adam Dent said 450 homes had been destroyed in the Kinglake fires and another 200 had burned across the state.

About 400 Red Cross volunteers were working around the clock to offer emotional support for the victims.

"As you can imagine, it's a pretty traumatic situation to walk in with nothing but the clothes on your back," Mr Dent said.

"A lot of them are breaking down as they come in, and we are getting a lot families.

"I think everyone has been caught unaware in terms of how enormous the devastation has been.

"We have been fortunate we have a lot of people who are very ready, but I don't think anyone could really be ready for something this big."

To donate to the Victorian Bushfire Fund, call 1800 811 700. People can also donate online at redcross.org.au

People trying to contact lost relatives can ring the Red Cross's State Inquiry Centre line on 1800 727 077.

Mr Dent urged callers to be patient if lines were engaged.

An insurance taskforce has been set up to help people who have lost homes.

The Insurance Council of Australia says it's too early to estimate the total bill and the number of claims from the fires.

Insurers already have call centres operating to help policyholders get the claims process underway quickly, and assessors will be on the ground as access to affected areas is opened, the Council says.

It says policyholders shouldn't be concerned if their insurance documents have been lost or damaged in the fires, as insurance companies keep electronic records.