A semi-truck fire that sparked up on Northbound 99 near South Union Avenue closed down several lanes of traffic Tuesday morning. According to California Highway Patrol, only one lane is open at this time.

It started around 5:15 Tuesday morning when a semi-truck became disconnected with it's trailer and the trailer caught fire. CHP and Kern County Fire crews responded to the scene.

No word yet on when lanes will be reopened.

This is a developing story.