HOUSTON -- Part of U.S. Highway 90 remained closed Monday after a train derailment in Fort Bend County, authorities said.

The accident happened at about 7 p.m. Sunday on Highway 90 between Harlem and Pitts streets near the town of Richmond, Texas, according to KPRC Click2Houston.com.

Investigators told News2Houston that 32 Union Pacific rail cars derailed, spilling their cargos onto the freeway.

The cargo was a large shipment of gravel that authorities said was not considered a hazardous material.

No injuries were reported.

The cleanup forced highway crews to shut down one of the westbound lanes of the highway, which were expected to be reopened Monday afternoon.

The accident tied up traffic for morning commuters.

Union Pacific officials told News2Houston that the cleanup is expected to take two days.