NEW YORK (AP) — A New York City teacher was struck in the hand by a stray bullet Wednesday as he set up his classroom for the start of school, police said.

The 33-year-old teacher was inside his sixth-floor classroom at a middle school in the Bronx just before noon when a bullet flew through a window and grazed his right hand, police said. He was taken to a hospital for treatment and released.

There were no students in the building, since classes start Thursday in New York City public schools.

Police said a single bullet was recovered inside the classroom. The unidentified shooter likely fired from an elevated surface, possibly a rooftop, but is not believed to have been aiming for the school, according to Keiyon Ramsey, a deputy police chief in the Bronx.

“This egregious display of violence is both upsetting and reprehensible," a spokesperson for the city Department of Education said in a statement. "NYPD immediately responded to the scene where one educator sustained non-life-threatening injuries. We will provide additional support to this school community.”