German killer's warning: I'm going to give them hell

WINNENDEN, Germany (CNN) - The teenager who killed 15 people in Germany issued a warning about the attack on the Internet the night before his rampage, saying: "I have got a weapon here and... I am going to go to my former school and give them hell."

Police said Tim Kretschmer, 17, made the threat during an online conversation with another teenager before Wednesday's attack.

Kretschmer said: "Everyone laughs at me. No one recognizes my potential. I mean this seriously. I have got a weapon here and tomorrow I am going to go to my former school and give them hell.

"Maybe I would escape, keep your ear to the ground. You'll hear from me tomorrow morning. Just notice the name of the place, Winnenden. Don't say anything to the police."

The other teenager replied: "Laugh out loud, course you will."

"I need to see some pictures before I believe it," the teenager added.

Heribert Rech, interior minister of the state of Baden-Wurttemberg, told journalists that media reports indicated a teenager from Bavaria reported the Internet conversation to his father.