The intersection of Frankston-Dandenong Road, Hall Road and Lathams Road in Carrum Downs is closed in all directions, due to a collision and rollover.
Emergency services are directing motorists to take left turns only through the intersection, after which drivers can U-turn to continue their journey.
Motorists have been encouraged to avoid the area and use Thompsons Road, the Western Port Highway, the Mornington Peninsula Freeway or Ballarto Road instead.
This closure is under Victoria Police control.
The road will re-open when investigations are complete and it is safe to do so.
A signals team will adjust traffic lights as needed to minimise congestion in the area.
Real-time traffic conditions are available at traffic.vicroads.vic.gov.au or via the VicTraffic mobile app.
The latest public transport information and network status is available at ptv.vic.gov.au or in the PTV mobile app.