HOUSTON -- I-45 Gulf Freeway's inbound mainlanes were shut down for nearly five hours Wednesday morning after a fiery crash involving a big rig and a hazmat spill.

Houston TranStar reported the crash happened after 1 a.m.

According to Houston Police, a big rig driver said his truck caught fire while he was driving, causing him to hit a pickup truck that was stalled on the shoulder. The big rig then spilled a load of concrete on the freeway.

Photos: Fiery big rig crash on I-45 Gulf Freeway

Witness video showed the scene just after the crash as spilled fuel burned on the pavement.

The crash was cleared out of the way, and the freeway fully reopened at about 6 a.m.

Police say the big rig driver was not hurt. The driver of the pickup was taken to the hospital but is expected to survive.

The crash remains under investigation.

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