Johnson is accused of punching a female FSU student at a Tallahassee bar Wednesday night, sources said.
According to the sources, Johnson was involved in an argument with the woman after she cut in front of him while they were waiting to order drinks at a bar near the FSU campus. Witnesses told police the woman raised her arms and then Johnson grabbed them and punched her in the face.
Johnson, from First Coast High School in Jacksonville, Florida, has not been charged with a crime. Police did not interview Johnson on Wednesday night because he had left the bar. Tallahassee attorney Tim Jansen, who has represented FSU student-athletes in the past, told ESPN.com on Thursday that he was unaware of the incident.
A Tallahassee Police Department spokesman sent a heavily redacted incident report to ESPN.com on Thursday. The incident report redacted the alleged suspect's name and a witness' name. The woman's name was not redacted.
The woman, a 21-year-old FSU student, declined comment when reached by ESPN.com. She was treated by police and security officials at the scene and declined further medical treatment.
Johnson, who enrolled at Florida State in January after graduating early from high school, isn't thought to be one of the main contenders for FSU's starting job this season. Junior Sean Maguire and Notre Dame transfer Everett Golson, who enrolled at Florida State this summer, are believed to be the main contenders to replace 2013 Heisman Trophy winner Jameis Winston, who was the No. 1 pick by the Tampa Bay Buccaneers in April's NFL draft.
Winston had his own share of legal issues while at Florida State. He was accused of sexual assault in December 2012, though after a lengthy investigation he was never charged. He currently faces a civil suit in the matter.
In April 2014, Winston was issued a citation after shoplifting crab legs from a Tallahassee grocery store. He was ordered to complete 20 hours of community service and was suspended from playing for the baseball team until he completed the service.
Freshman Deondre Francois of IMG Academy in Bradenton, Florida, also joined FSU's quarterback competition this summer. He was ranked the country's No. 3 dual-threat quarterback and No. 42 prospect overall in the ESPN 300.
Johnson, who was named the 2014 Florida Dairy Farmers Mr. Football, was ranked the No. 7 dual-threat quarterback as a senior. He passed for 3,710 yards with 47 touchdowns while running for 398 yards with nine scores, leading First Coast High to a 12-1 record last season. He finished his prep career with 11,697 passing yards, 131 touchdown passes and 23 rushing scores.