State troopers responded to the scene, on I-405 near the 8th Street exit, a few minutes before midnight on Thursday after receiving reports of a serious crash.
Arriving at the scene, troopers and medics found a semi truck and trailers lying on their side at the exit, with dozens of packages and fuel spilled across the pavement. Three other damaged vehicles also were at the scene.
"What a mess!" one trooper tweeted from the scene.
The driver of the semi truck and one other person were taken to the hospital with non-life-threatening injuries.
A preliminary investigation found that the semi with two trailers was heading north on I-405 in the right lane when it merged over to the left to pass another vehicle.
Somehow the semi driver lost control, veered back across the right lane and slammed into a guardrail and jersey barrier at the off-ramp to Northeast 8th Street and Northeast 4th Street.
The rear trailer came loose from the force of the impact and crashed onto its side across two lanes of the freeway. The semi tractor and front trailer came to rest in the middle of the off-ramp.
Meanwhile three other vehicles following behind the semi crashed into each other and wound up on the right shoulder of the freeway.
Troopers at the scene said it does not appear drugs or alcohol were a factor in the crash.
It took several hours to investigate the crash and clear the mess from the freeway and the off-ramp. All lanes have now reopened.