DALLAS (CBSDFW.COM) – A big rig crash has shutdown the eastbound lanes of Interstate-20 in the southern part of Dallas County.

The driver of the gravel hauler is believed to have hit an overhead sign near St. Augustine Drive just before 9:30 a.m. The impact knocked the sign down, flipped the trailer of the semi on it’s side and spilled large rocks, gravel and hydraulic fluid over the freeway.

i 20 rock hauler 8 Gravel Hauler Crashes Into I 20 Sign, Spills Rocks Over Freeway

(credit: CBSDFW.COM/Chopper 11)

The closure has eastbound traffic backed up for miles. Click here to check the latest traffic conditions in the area.

In addition to Dallas Fire Rescue and police, the Texas Department of Transportation (TxDOT) and hazardous materials crews are at the scene.

i 20 rock hauler 7 Gravel Hauler Crashes Into I 20 Sign, Spills Rocks Over Freeway

(credit: CBSDFW.COM/Chopper 11)

There have been no reports of injuries and investigators are still trying to find out what caused the crash.

Officials with the Dallas County Sheriff’s Office say the freeway will remain closed until the mess can be cleaned up — and they anticipate it being several hours before the highway completely reopens.