A bus driver unaffiliated with the team but hired to drive the Pirates from Chicago to Milwaukee late Thursday was charged with driving under the influence, Illinois law enforcement officials said.

Around 11:30 p.m. after a game at Wrigley Field, state troopers pulled over the team bus on the right shoulder of I-94 northbound at Dempster Street — about 25 minutes from the ballpark — following reports of erratic driving.

Illinois state police said Ronald Funderburke, 61 of Shelby, N.C., was not following the designed escort, and they initially thought he might’ve experienced a medical emergency.