Reports suggest that the explosion was caused by a missile from an Israeli drone, targeting an unarmed fighter who had moved to stand outside the house.B'Tselem:
[Al Jazeera correspondent] Chater said there appeared to have been two missiles fired from the drone.
The first missile targeted four fighters, armed with a Kalashnikov rifle and carrying a bag containing rocket-propelled grenades.
He said the men had put the bag down and the grenades were later recovered, intact, by B'Tselem.
"It [the bag] did not explode. There was no secondary explosion as the Israeli military are saying.
"Three men out of the four were injured by that first missile attack ... the fourth one, unarmed, walked down the street," he said.
"He was killed by a second blast and that second blast from the drone caused the deaths of the mother and her four children."
B'Tselem’s investigation indicates that an Israeli aircraft fired a missile at three armed Palestinians standing on a street in the northern section of Beit Hanun, wounding them and a nearby civilian. About a minute later, the aircraft fired a second missile, this one at a fourth armed man, who was about fifteen meters from where the first missile landed, and about one meter from the gate of the Abu Me'tiq family’s house. This missile killed the fourth armed man and the five members of the family.There are still many inconsistencies between Al Jazeera's and B'Tselem's accounts, as well as the PCHR initial report, but all agree that the Palestinian Arab version was complete fiction.
In its letter, B'Tselem states that the material it has collected, including an analysis of the area, photographs of bodies and eyewitness accounts, raise doubt about the IDF Spokesperson’s contention that a secondary explosion is what killed the family. B'Tselem called on the IDF Spokesperson’s office to publish all the material in IDF hands that documents the incident, especially the UAV photos, which could prove or refute this claim.
It is also curious why B'Tselem doesn't mention the bag of RPGs that Al-Jazeera claims B'Tselem recovered. I emailed B'Tselem to see if they have any more information, or, especially, photographs of the house, and asking them to release all of their information just as they demand the IDF does the same. The information can be looked at objectively; their results cannot because they might be colored by a reliance on "witnesses" who are not so interested in the truth.