DALLAS (CBSDFW.COM/AP) — Federal safety investigators say a Texas driver suffering from “acute sleep deficit” failed to maintain his lane and caused his passenger bus to careen out of control, causing a wreck that killed nine people and injured nearly 40 others in 2016.

The National Transportation Safety Board released its final report on the crash Tuesday. The agency determined the bus left the road and rolled when the 29-year-old driver overcorrected and abruptly braked.

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An OGA Charters bus crashed just north of Laredo that killed eight people

Inspectors say the OGA Charters bus crashed north of Laredo in rainy conditions, but had an inoperable antilock braking system.

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The bus began its trip in Brownsville, in far South Texas, and was en route to the Kickapoo Lucky Eagle Casino in Eagle Pass in May 2016.

Seven passengers died at the scene. Two others died later. Among those on the bus were several employees of the school district in La Hoya, located about 130 miles south of Laredo. The district said six of their employees, including one who died, were on the bus as part of a weekend trip that was not school sponsored.

The driver was injured i the crash, but survived the wreck.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)