Bus driver freed after serious crash east of Melbourne

A female driver has been freed after becoming trapped when a bus crashed into a tree east of Melbourne.

Authorities were called to the crash around 7.30am today on Monbulk Road in Monbulk, east of Melbourne.

The bus collided with a tree, trapping the driver.

Paramedics arrived on scene and freed the woman, believed to be in her 40s.

There were 11 passengers on the bus, who were assessed by paramedics.

It's not clear what caused the crash.

Authorities have warned of delays while they investigate the crash.