Sounds like this is another of those incidents that had multiple angles to it. The status of "refugee camp" is disputed by many because it's actually a city with buildings.
Then the Israelis are claiming they didn't strike the civilian areas, but an underground stronghold that unfortunately had lots of ammunition in it and blew up, collapsing the tunnels and taking down all those buildings, after having warned the citizens to leave.
Personally I haven't seen enough to work out what the truth really is here, but there definitely seems to be a bit more to it than simply "refugee camp blown up by Israel".
Is it actually a refugee camp? Did Israel give warning? Could the citizens have feasibly left even if so? Did Israel really target just a military installation and the rest was an accidental by-product? Did they know the destruction it would cause and do it anyway?
The propaganda and spin from both sides is almost impenetrable I'm finding.