THE threat to the Hattah township from a 10,000ha fire in Victoria's northwest has eased.

Residents of the tiny town of Hattah, 500km northwest of Melbourne, fled late yesterday ahead of the large bushfire, which was sparked by a lightning strike in the Murray Sunset National Park.

While the threat has eased, crews have remained to protect the town.

The fire grew to cover more than 10,000ha yesterday afternoon, pushed along by a strong north west wind and a westerly wind after the change.

The fire has also burned private property near the Hattah-Kulkyne National Park, but the DSE said it had mostly been kept within the park due to fuel-reduction burns on private land.

The Calder Highway was reopened at 11am today, at a restricted speed of 60km/h due to smoke and emergency vehicles using the road.

More than 100 DSE and Country Fire Authority firefighters are on the scene.

A second fire near Walpeup has burned about 1000ha and was contained by crews last night.