The source, who is reportedly a lieutenant colonel within Hamas, tells the BBC that large parts of Hamas' top layer and infrastructure have been struck down as a result of Israeli attacks. Through voice messages sent to the BBC from within the Gaza Strip, the source describes a more or less total collapse of what he calls security in Gaza.
"Let us be realistic – there is hardly anything left of the security structure. The majority of the leadership, about 95 percent are now dead...", says the source in a voice message.
In the power vacuum that has arisen with Hamas' weakening, six armed groups or clans have emerged "everywhere" on the Gaza Strip, says the lieutenant colonel.
One of the militia groups, Abu Shabab, is led by its leader Yasser Abu Shabab from the West Bank and is a rival to both Hamas and regional actors.
Sources on the Gaza Strip tell the BBC that Abu Shabab is coordinating with other armed groups to remove Hamas from power on the strip.
Hamas, in turn, has put a high price on Yasser Abu Shabab's head, as they fear he could become a unifying figure for Hamas' many enemies.
