Eastbound traffic on Intrastate 84 is almost a standstill, due to two vehicles that have rolled over between Cloverdale and Five Mile Roads in west Boise.
The accident happened about 12:45 pm.
Idaho State Police troopers, Boise Police officers and paramedics are all on the scene.
Drivers are asked to avoid that stretch of the Interstate, if possible.
No further details were immediately available.