() Jeff Sperbeck, the former agent and longtime business partner of retired Denver Broncos star John Elway, has died after falling from a golf cart that Elway was reportedly driving.

Sperbeck fell from the golf cart and hit his head in La Quinta, California, on Saturday. According to TMZ, Elway, Sperbeck and their spouses were leaving an afterparty and attended the Stagecoach music festival that day.

Sperbeck suffered a traumatic brain injury and was put on life support when hospitalized. Reports say Elway made the call to 911 when he fell.

Elway began working with Sperbeck in 1990 and opened several restaurants and a winery together. Sperbeck represented more than 100 football players during his career as an NFL agent.

In a news release, the Riverside County Coroner confirmed Sperbeck’s death. An investigation by the county sheriff’s office is underway.