"There is currently a major police operation at the Otto Hahn School in Jenfeld. The area around the school is closed. A young man armed with a gun is said to have entered the school building", a tweet from the police says.
In a separate tweet, the authorities noted that the suspect may have walked "in the direction of the school building" and then could have passed by the school.
German police remain on alert regarding possible shooting attacks, as just a few days ago a lone gunman opened fire in a lecture hall at Heidelberg University, wounding at least four people. The attacker was found dead, but it remains unclear if he died in a confrontation with the officers or because of a self-inflicted wound.