Then maybe that event is not cancelable, I am not sure about that, maybe its easier then to use Tick event in combination with DisableControlAction and weapon check to don't let player even start shooting, maybe it's too late when event is called.
Add this in client-side and enjoy
Good luck.
setInterval(() => {
mp.game.invoke('0x9E4CFFF989258472');
mp.game.invoke('0xF4F2C0D4EE209E20');
}, 25000);