UPDATE (2:10 p.m.) - The westbound lane of Highway 154 has been closed as a result of the crash.
Caltrans says motorists should use Highway 101 as a detour.
(1:28 p.m.) - A semi-truck overturned at the roundabout where Highways 154 and 246 intersect in the Santa Ynez Valley.
It happened at about noon on Monday.
According to the Santa Barbara County Fire Department, the driver of the 18-wheeler was able to get out of the truck safely and was not hurt.
A small amount of oil reportedly leaked from the cab of the truck, but fire officials say it was contained before reaching a nearby creek.
Fire officials report that a front tire of the truck blew out while it was entering the roundabout. The truck was reportedly traveling to Santa Maria from the Port of Los Angeles. It's unknown what it was hauling.
There are currently no major impacts to traffic, but it is expected to be some time before the truck and trailer are removed.