Motorists are advised to avoid the intersection of Roe Highway and the Great Eastern Highway Bypass after a truck driver suffered a medical emergency this morning.
The driver was turning right onto the bypass when he stopped his truck in the middle of the intersection in Hazelmere.
St John Ambulance paramedics rushed him to Swan District Hospital but it is understood he has since died.
Traffic lights are flashing amber at the intersection and police are directing traffic.
A Main Roads spokeswoman urged drivers to take an alternate route.