Hamas says one of its senior officials is critically injured after accidentally shooting himself while cleaning a firearm.
Initial reports, some by the group's official media, said Imad Al Alami had died of natural causes. But Hamas subsequently said he was wounded in a gun accident.
Mr Alami, 62 is a former member of Hamas's policy-making politburo and a senior official.
Israel exiled Mr Al Alami from Gaza in 1994. He spent most of his time in Syria before returning in 2012, after Hamas abandoned its longtime base in Damascus.
After Israel's 2014 war on Gaza, Mr Al Alami travelled to Turkey for treatment for an unspecified injury that Hamas said he had suffered during the war.