The trailer of a semi-truck rolled over on northbound Interstate 5 in Federal Way on Tuesday morning, causing traffic back-ups.

The collision occurred at approximately 7 a.m. at South 320th Street. The off-ramp to South 320th is open; however, the right lane was blocked off as of 8:15 a.m., according to Washington State Patrol trooper Chris Webb.

Webb said the axle from the trailer came off and caused the truck to strike the guardrail and spin out of control.

There were no injuries.