Former Oakland Raiders Pro Bowl defensive lineman Chester McGlockton has died. He was 42.

McGlockton, who was a defensive assistant coach at Stanford the past two seasons, died overnight, the school said. The cause of death was not immediately announced, though one report said he died of a heart attack.

“Everyone in the Stanford Football family is deeply saddened by the passing of Chester McGlockton,” Stanford coach David Shaw said in a statement. “For the past two seasons, Chester has been a valuable member of our football staff and a wonderful friend to us all. Our thoughts and prayers go out to Chester’s wife Zina and their two children.”

A native of Whiteville, N.C., McGlockton starred at Clemson before being selected 16th overall by the Los Angeles Raiders in 1992. He played 12 seasons in the NFL with the Raiders, Kansas City Chiefs, Denver Broncos and New York Jets. He made all four of his Pro Bowl appearances while with the Raiders from 1994-1997.

McGlockton’s best season came in 1994, when he had a career-high 9½ sacks with three forced fumbles and 48 tackles.

“The thoughts and prayers of the Raider Nation are with the McGlockton family during this difficult time,” Raiders CEO Amy Trask said.

After his playing career, McGlockton returned to school and earned his undergraduate degree from Tennessee-Martin in 2010. He had lived in San Ramon, Calif., with his wife and two children while serving as a Stanford defensive assistant the last two seasons.

Before joining Stanford, McGlockton also spent time as an assistant coach at Hayward’s Chabot College.

Funeral arrangements were pending.