PCHR finally issued a press release, and the cause of the explosion was a (probable) Islamic Jihad rocket falling on their house.
At approximately 19:10 on Thursday, 13 March 2014, a home-made rocket landed on a house belonging to the family of Isma'il Abdul Fattah Mohammedin (35) on al-Wadi Street in Beit Hanoun town in the north of the Gaza Strip. The rocket made a hole whose diameter was one meter in the southeastern wall of the house and exploded inside. As a result, Aisha Atiya Mohammedin (52) sustained shrapnel injuries and amputation to the right hand, and she died because of the serious injuries at approximately 00:30 on Friday, 14 March 2014, at Shifa Hospital in Gaza City.Remember that Islamic Jihad claimed to shoot 130 rockets at Israel (and other terror groups, mostly Fatah, about 20 more) but Israeli officials only counted 60 rockets reaching Israel. In other words, some 60% of the rockets fired apparently exploded on the ground or fell short.
Additionally, another 5 civilians, including 3 children, living in the house were injured.
In a two week period in January, 37% of rockets fell short. I counted an 83% failure rate for two weeks from February 20-March 5.
Even though more Gazans than Israelis have been killed by Gaza rocket fire, no one is protesting how dangerous Gaza rockets are - to Gazans.