Tim Kretschmer was born on July 26, 1991. He grew up in the town of Leutenbach, Germany, where he lived with his parents. As he grew up, he struggled academically and graduated from Albertville Realschule in 2008 with poor grades. His low grades made it hard for him to find an apprenticeship. He then attended a commercial high school called Donner + Kern in Waiblingen, where he hoped to prepare for a career in business.

Several reports describe Kretschmer as having depression. Friends mentioned that he was a lonely and frustrated individual who felt rejected by those around him. He was quiet and began to withdraw from his classmates over time. Despite his struggles, Kretschmer had a passion for table tennis. He aimed to become a professional player and trained at a local sports club from 2000 to 2003. His coach recalled him as somewhat spoiled and noted that Kretschmer had a difficult time accepting defeat during matches. He would often throw tantrums when he lost.

In addition to table tennis, Kretschmer enjoyed playing video games, particularly Counter-Strike. He also liked to play with airsoft guns and shot them in the forest behind his house and in his basement. Reports say that he often played video games after school, including poker with his friends. On the day of his death, he was playing Rollercoaster Tycoon 2 online using the name "JawsPredator1."

Kretschmer's mental health issues were recognized by a therapist, and he had received treatment for depression in 2008. However, he ended his therapy sessions and did not continue with any follow-up treatment. His family disputed claims that he had received psychiatric help. He had a history of angry outbursts and expressed feelings of anger and isolation. Despite not having a criminal record, his friend described him as someone who felt very much alone in the world.

On the morning of March 11, 2009, Tim Kretschmer entered the Albertville-Realschule in Winnenden, Germany, and began his attack around 9:30 AM. Armed with a 9 mm Beretta 92FS pistol that he had stolen from his parents, Kretschmer targeted two classrooms and a chemistry laboratory on the upper floor. In the first classroom, he shot five students in the head at close range during a Spanish lesson. He then moved to another classroom, where he killed two more students and injured nine others; two of these students would later die from their injuries.

After reloading his weapon, Kretschmer attempted to shoot off a locked door but failed. He then continued to the chemistry lab, where he shot the teacher. Many students managed to escape by jumping out of windows as he wreaked havoc in the school, firing more than 60 rounds. A coded announcement was made by the school headmaster to alert the teachers to the situation, allowing them to lock classroom doors. Once police arrived just minutes after the shooting began, Kretschmer shot at them while fleeing the building, killing two teachers in the hall as he exited. In total, he killed twelve people at the school before leaving the scene.

After escaping the school, Kretschmer killed a 56-year-old gardener from a nearby psychiatric institution. Large police forces were mobilized to search for him, but he managed to evade capture for some time. Around 10:00 AM, he carjacked a Volkswagen minivan from a car park, forcing the driver to take him toward Wendlingen. During the drive, he spoke casually about finding more places to attack while loading his pistol magazines.

The situation escalated further when Kretschmer reached Wendlingen and entered a car showroom. There, he threatened a salesperson and demanded the keys to a vehicle. The salesperson fled, and Kretschmer shot and killed another salesperson and a customer in the showroom. A shootout began when police arrived, and Kretschmer continued to fire at law enforcement officers, injuring two in the process.

In the chaos, witnesses saw Kretschmer shoot at random targets before he ultimately turned the gun on himself, ending the ordeal. He had fired a total of 112 rounds during the entire incident, and when he died, he still had unused ammunition with him. Overall, Kretschmer's actions resulted in a total of 15 deaths, including nine students, three teachers, and two victims in the later shootout at the car dealership.