A fast-moving bushfire west of Melbourne has claimed several buildings, with at least 40 more houses under threat. Three firefighters and one resident have been reportedly injured.

The Country Fire Authority has issued an emergency warning stating that the fire is a risk to lives and homes.

The grassfire, about 90 hectares in size and currently very much out of control, is expected to impact Dalmore East, Officer, Officer South, Rythdale and Cardinia before 5.15pm (AEDT) on Wednesday, March 27.

The warning, issued by the CFA in its Web site, said the fire has actually crossed Lecky Road and is now moving southerly towards Cardinia.

"Fire crews are currently working the head of the fire just south of Lecky Road. There is a risk to lives and homes, follow your bushfire survival plan."

"If you plan to leave, or you are not prepared and there is a safer place nearby, leave now if it is safe to do so."

In western Victoria, at Dereel, about 30km southwest of Ballarat, two homes have been lost, according to still yet to be confirmed reports.

Water-bombing aircraft have been brought in to control the blaze which has grown to 280 hectares.

The fire is expected to affect Dereel, Warrambine and Corindhap any moment from now.

"It's a fire that's being fanned by very strong winds. So up to 95 kilometres at the fire ground. So this combination of high temperatures, dry grass and strong winds is proving difficult," Lee Miezis, state control centre spokesman, said.

"We understand that there's at least 12 houses are currently under threat and there are unconfirmed reports of property loss."

"Certainly under the conditions that they're experiencing out there with gusting winds and a fast-moving grassfire there is certainly the risk of spot fires and people do need to be very alert in that area."