The suspect, who opened fire at around 7:59 am (0459 GMT) in Turgutlu, an area west of the resort city of Izmir, was detained by security forces following the attack, the governor's office said in a statement.
One of the wounded was in serious condition, it said.
An unidentified suspect opened fire in the area for an unknown reason before fleeing the scene, according to the reports.
Police and medical teams were on the scene and authorities were searching for the attacker, while security around the school has been tightened.
It marked the latest such shooting in Turkey.
In April, a 14-year-old opened fire at a school in the Kahramanmaras province, killing nine students aged 10 and 11 and one teacher. The youth attacker died at the scene.
In a separate incident in the southeastern province of Sanliurfa, a former student opened fire at his former high school, wounding 16 people, before taking his own life when confronted by police.
The attacks have sparked public outrage. President Recep Tayyip Erdogan has dismissed a deputy education minister and said the government would introduce measures, including restrictions on gun ownership.
