@Olivier5,
I know it because I pay attention to the news.
Whenever Palestinians are killed, they are nearly always killed while trying to murder innocent people.
I guess there is collateral damage sometimes too. But even the collateral damage comes from justified defense against Palestinian murderers.
Luckily the Security Fence does a good job of keeping the Palestinians locked away so they can't harm people so much. The killing has been greatly reduced compared to the time before the Security Fence was built.