Police told the Reno Gazette-Journal that an initial investigation showed a group of Nevada football players got into a fight with another group of people.
That other group got into a car. When Wimberly approached the car, someone inside shot him, police said.
The other group fled in the car after the shooting.
Nevada coach Chris Ault said he had talked to Wimberly and the doctor who performed surgery on him.
"Although his condition is serious, he is very fortunate," Ault said Saturday in a statement. "I have met with the players who were involved. They have no idea who shot Brandon and have every intention of being cooperative with the Reno Police Department. My biggest concern is the health and welfare of Brandon."
Speaking to the Reno newspaper, Police Lt. Keith Brown also said Wimberly's injuries were serious.
"They're not life-threatening, but they're probably life-changing," Brown said.
Wimberly, the WAC freshman of the year in 2009, had 41 receptions for 482 yards last season.
"We know the Reno Police Department is conducting a complete investigation and have instructed our student-athletes to cooperate fully with the police," Nevada athletic director Cary Groth said in a statement. "It is an unfortunate situation and we wish Brandon a speedy recovery from his injuries."
Andrea Adelson covers college football for ESPN.com.