A bullet crashed through the window of a Bronx middle school classroom Wednesday, hitting a teacher in the hand as he prepared the room for the first day of class, cops said.

Multiple gunshots rang out on the street outside Middle School 391 on Webster Avenue just before noon, according to law enforcement sources.

A bullet darted into the 33-year-old teacher’s classroom on the sixth floor, striking him in the right palm, Deputy Chief Keiyon Ramsey said. 

The teacher was taken to St. Barnabas Hospital in stable condition.

There were no students in the building or near the school at the time of the shooting, Ramsey added.

Classes are set to begin Thursday. 

Police said the school did not appear to be the targeted, but safety agents and cops will be on scene for the start of the school year.