Updated

Hamas is vowing revenge after blaming Israel for an explosion that killed six of its fighters.

The Islamic militant group, which rules Gaza, said Sunday that Israel "will pay a heavy price" for the explosion the night before.

Gaza media initially reported the blast as a "work accident," implying the militants were killed while producing or handling explosives.

But Hamas now says the militants, including two commanders, were killed "dismantling booby-trapped spying equipment planted by Israel during the past decade in Gaza." It did not elaborate or provide any evidence.

Israel's military declined comment.

Hamas' supreme leader, Ismail Haniyeh, was among thousands of Palestinians who attended the militants' funerals.