Two bombs, they claim, were used in the attack: one for the Hamas commanders, which can be considered a legitimate target and the other was used to destroy an ammunition dump nearby. Also a legitimate target of war, it can be said. However, the proximity of the warehouse to refugees meant the IDF knew there'd be collateral damage and went ahead with the strike anyway, showing their total disregard for civilian casualties as the assault on Rafah goes ahead.
Why?
If they knew the commanders would be there at a certain time, how is it not possible to send a special forces team in to assassinate them and minimise the risk to Palestinians sheltering from the assault on Rafah? When the British Army found an IRA hideout during The Troubles it wouldn't drop a bomb through the roof or send an rpg through the window. Great care was taken to avoid civilian casualties, yet the Zionist campaign is deliberately designed to cause maximum devastation regardless of how many innocent people are nearby.
There is no justification for these war crimes under International Law.