On Thursday, at least 27 Palestinians were killed at an Israeli air strike of an atmosphere, turned into a northern gas school, according to the Hamas Health Ministry.
Israeli defense forces said they were heading for “prominent terrorists” at the Hamas Command and Control Center in the area.
Jake Horton at BBC Verify explains what we know about the incident after looking at videos posted online.
Additional reporting by Richard Erwin-Brown, Joshua Cheethham, Emma Pengeli and Sherry Ryder. Made by Aisha Seumbhi. Mark Edwards graphics.