One of the great running backs in Iowa State history has died unexpectedly in Texas. Ennis Haywood, 23, a member of the Dallas Cowboys practice squad, died Sunday.

Haywood, the #5 all-time rusher in ISU football history, had been on life support at an Arlington, Texas, hospital since being rushed there unresponsive in the early hours of Saturday morning. He was a Dallas native and former standout at Carter High School.

Family members told doctors Haywood had begun vomiting in his sleep around 4 a.m. Saturday. He stopped breathing around 6 a.m. and was taken by ambulance to a hospital a short time later. He had been in intensive care on life support since then.

As a Cyclone, Haywood rushed for 2,862 yards and was the Big 12's leading rusher as a junior and senior in 2000 and 2001. He scored 27 touchdowns in his Iowa State career, sixth on the all-time charts. Haywood played on two bowl teams for ISU, rushing for 74 yards and scoring a touchdown in the Cyclones' 37-29 win over Pitt in the 2000 Insight.com Bowl. He rushed for 125 yards in Iowa State's 14-13 loss to Alabama in the 2001 Independence Bowl.

His biggest day as a Cyclone, yardage-wise, came in 2000 when Haywood rushed for 241 yards on 39 carries as Iowa State won at Baylor, 31-17. He gained 219 yards and scored two touchdowns in a 31-28 win at Ohio in 2001 and had 214 yards on 23 carries in a 39-20 win over Missouri in 2000.

Other big games for Ennis included 185 yards and four first-half touchdowns in a 49-7 romp at Kansas in 2001, three TDs and 196 yards in a 28-14 victory over Oklahoma State in 2001 and 190 yards on 29 carries in a 38-17 victory over Kansas in 2000.

"Like everyone in the Cyclones' football family, we are shocked and saddened beyond words," ISU football coach McCarney told the Associated Press on Sunday. "Ennis was one of the classiest gentlemen there has ever been, on and off the field. He was an unbelievable competitor, and one of the most tenacious football players I've ever been around."

Haywood was an undrafted free agent signing for the Cowboys in 2002. He led Dallas in rushing during the pre-season last year and earned a spot on their practice squad as a result. He signed a new contract with the Cowboys earlier this year.

The cause of death is unknown as of Sunday evening, according to a hospital spokesperson. Funeral services are pending.