Hamas's military wing said today an explosion that killed eight Palestinians in the Gaza Strip was an accident that occurred as militants prepared to carry out a bomb attack.
Hamas initially blamed yesterday's explosion on an Israeli air strike, but the Israeli military denied involvement.
The blast flattened the two-storey house of Hamas bomb-maker Ahmed Hamouda in the northern town of Beit Lahiya, killing six Hamas fighters, a four-month-old girl and a civilian. One of the six men died of his wounds today.
Hamas said Hamouda was not killed in the explosion.
"An error occurred and led to the explosion and they were martyred," said Abu Ubaida, a spokesman for the Izz El-Deen al-Qassam Brigade, Hamas's armed wing, saying the exact cause was unclear because all those involved were killed.
The brigade said in a statement the militants were putting the final touches to what they called a "special jihadi mission".
Hamas fired about 20 rockets at Israel shortly after the explosion in Beit Lahiya, an area frequently used by militants to launch rockets into the Jewish state.
The Israeli army killed five militants in two other operations in the Gaza Strip on Thursday, bringing the number of Palestinian dead to 13.
Egypt is trying to broker a ceasefire in the Gaza Strip between Israel and Hamas but progress has been stalled by disagreement over the scope of the deal.