In the early morning of February 5th, 1943, the attack was carried out by Kastein and a CS-6 member, the student Jan Verleun. Verleun fired the two fatal shots at Seyffardt, in the doorway of Seyffardtsí house in Scheveningen. On February 12th, the following was published in "Volk en VaderlandĒ:
"In the evening of the 4th (actually early in the morning of the 5th) February, suddenly two individuals in the darkness, were in front of him and asked if he was General Seyffardt. There was no hesitation. The answer loud and clear: "Yes, I'm General Seyffardt ď. Two shots and he collapsed, seriously injured. With exertion of his utmost powers he managed to communicate his injuries by telephone. One of his last wishes was not to shoot hostages for his sake. He has had the great privilege to fall as a soldier at an age when others die in their beds. This fills us with emotions and tempers our grief."
The next day, February 6th, Seyffardt died of his injuries in the hospital. A few days after his death, a farewell meeting with great military honours was organized for him in The Hague. Subsequently, a ceremony was held at which only his family and a few friends were present before he was cremated.