Robertson was a former first-round draft pick and six-time Pro Bowl linebacker in the National Football League for the Los Angeles Rams from 1971 to 1978.
Robertson was rushed to UT Health-Athens and later died, according to the Texas Department of Public Safety.
According to DPS officials, around 10 p.m., a Lincoln Limousine, driven by Isiah Robertson Jr., 69, of Garland, was traveling north on State Highway 198 at an unsafe speed.
It veered off the road and skidded sideways before coming to a stop partially on the road. A truck struck the limo and pushed it into an oncoming traffic lane, where it was struck again by another vehicle.
Directly before his death, Robertson had been speaking at a banquet for the Grand Prairie High School athletic program, where the school says he would take students under his wing. The truck driver was treated for minor injuries and discharged. The conditions of the other two drivers, a 37-year-old man and a 21-year-old woman, were not confirmed. The crash was being investigated.
A Louisiana native, Robertson was selected with the No. 10 overall pick out of Southern University by the Rams in the 1971 NFL Draft. Robertson played eight seasons with the Rams, a span of time in which the team won six division titles, then finished his career with a four tenure with the Buffalo Bills.
The Rams drafted Robertson 10th overall out of Southern University in the 1971 National Football League draft and saw him blossom into a six-time Pro Bowler and 1971 Defensive Rookie of the Year.
Isiah Robertson played for the Los Angeles Rams from 1971 to 1978. He said the addiction caused him to lose his 14 homes, business and cars.
In a statement, the Rams said: "We are deeply saddened by the loss of one of our Legends, Isiah Robertson".
Robertson was the executive director of the Isaiah House in Mabank, a drug and alcohol treatment center.