UPDATE 9PM: The Calder Freeway is open.
Some speed restrictions may still apply in the area between Vineyard road and Gap Road in Diggers Rest.
Motorists are also warned fire trucks could be active in the area.
UPDATE 5.45PM: Outbound lanes on the Calder Freeway between Vineyard Road and Gap Road in Diggers Rest have been reopened with 60kmh speed restrictions in place.
All inbound lanes between Vineyard Road and Gap Road remain closed due to a grass fire.
VicRoads advises drivers travelling through the area to seek an alternate route and allow extra time.
The CFA has downgraded warnings for the Sunbury fire to advice.
The grassfire is deemed safe but fire crews will remain on the scene throughout the night to monitor any fire activity.
The CFA warns fire trucks will be working on roads and around the fire area.
UPDATE 5.30PM: The Calder Freeway remains closed in both directions but the CFA has downgraded its warning for the Sunbury/Diggers Rest area to a watch and act.
Fire crews have stopped the spread of the grass fire in the Sunbury area.
The next update is scheduled for 7pm.
UPDATE: 4.19PM: COUNTRY Fire Authorities have issued an emergency warning for Diggers Rest near Sunbury.
Emergency crews are battling a grassfire which is threatening homes.
The Calder Freeway has been closed in both directions between Gap Road and Vinyard Road near Sunbury.
Drivers heading to Melbourne are strongly urged to take an alternate route.
The Calder Freeway has been closed in both directions between Gap Road and Vinyard Road near Sunbury as fire crews battle a grassfire.
The CFA has issued an updated Watch and Act message for the Sunbury and Diggers Rest areas.
There are small grassfires in the Mitchell Street area of Sunbury.
This grassfires are currently not yet under control.
The fire is in the vicinity of Mitchells Lane, Moore Road, Regent Street and the Calder Freeway in Sunbury.
Residents who live directly next to grasslands in this area should consider moving one or two streets back.