The Sheriff’s Office for Marion County said the suspect was in custody following the early morning shooting at Forest High School in Ocala, Florida.
The Ocala Star Banner newspaper said one student shot another in the ankle.
“At this time we have one person injured and they are being treated by medics,” the Sheriff’s Office said.
The Ocala shooting came as students nationwide were urged to walk out of classes to mark the 19th anniversary of the 1999 school shooting at Columbine High School in Colorado which left 13 people dead.
The walkout has been organized by students at Marjory Stoneman Douglas High School in Parkland, Florida, where 14 students and three adult staff members were killed by a troubled former classmate on February 14.
The Parkland students have spearheaded a grassroots campaign for gun control which included marches by hundreds of thousands of Americans on March 24.
In Washington, students from area high schools planned to rally at the White House on Friday and march on Congress to demand action on gun control from legislators.