WA country town bushfire contained

Firefighters have contained the second blaze in a fortnight at a country town south of Perth, but a possible threat to lives and home remains.

An emergency warning issued for the western part of Waroona on Wednesday afternoon has since been downgraded to a watch and act alert after the bushfire was contained and brought under control.

But small pockets of bushland are still burning and firefighters have warned of embers blowing around properties.

People need to leave or get ready to actively defend their homes.

The fire started between Buller Road and Coronation Road, and has burnt along the banks of the Harvey River.

The Department of Fire and Emergency Services (DFES) said 123 hectares had been burnt.

The cause of the fire is unknown.

The blaze in the same part of Waroona on February 23 may have been deliberately lit, DFES said.