Senior Hamas official Imad al-Alami was in critical condition on Tuesday after accidentally shooting himself in the head while he was inspecting his weapon at his Gaza home, said a Palestinian medical source.
Alami has since been transferred to a Gaza hospital for treatment.
Hamas spokesman Fawzi Barhoum confirmed his injury, saying that he was in critical condition.
The 62-year-old Alami is a former member of Hamas' policy-making politburo and remains a top official.
Israel exiled 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 the 2014 war between Hamas and Israel, Alami traveled to Turkey for treatment for what Hamas said was an injury during the war. There were no details on how he was injured and lost a leg.