No group has yet claimed responsibility for the car bomb attack targeting Tawfiq Abu Naim
The head of Hamas's security forces in the Gaza Strip was injured on Friday when his car exploded in what the Hamas interior ministry called "a failed assassination attempt".
It did not immediately give details of the source of the explosion in central Gaza.
Hamas, which has been quick to blame Israel for similar attacks in the past, did not say who it believed was behind the bombing, suggesting it could also be the work of a radical Salafi group that opposes the Palestinian rapprochement. No group has yet claimed responsibility.
"Tawfiq Abu Naim, director general of the internal security forces, survived a failed assassination attempt Friday after his car was blown up in the Nusseirat refugee camp," a ministry statement said.
"He was moderately wounded and was treated in hospital," it added. "The security services immediately began investigations to discover the circumstances of the incident and to catch the perpetrators."
The incident comes at a time of tension within Gaza as its Hamas rulers are to start handing over power to the West Bank-based Palestinian Authority of Fatah leader and Palestinian president Mahmoud Abbas.
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The rival Palestinian movements signed a landmark unity deal this month aimed at ending their decade-long split.
The PA is due to resume control of the Gaza Strip by 1 December under the deal.
However, previous such attempts at reconciliation have repeatedly failed.
A major sticking point is expected to be Hamas's refusal to disarm its 25,000-strong armed wing.
Hamas took control of Gaza in 2007 in a near civil war with Fatah that followed an electoral dispute after polls won by the Islamist movement.
After Hamas's victory, it faced demands from the international community that it renounce violence and recognise Israel, which it refused to do.
Hamas has faced increasing isolation and deteriorating humanitarian conditions in the Gaza Strip in recent months, including a severe electricity shortage.