The leader of a Palestinian Islamist splinter group allied to al Qaeda was among 22 people killed when forces from the Gaza Strip's ruling Hamas movement stormed its strongholds around a mosque, Hamas said on Saturday.
Local civil rights monitors put the death toll at 28, with some 100 people wounded in Rafah, on the Egyptian border.
In the worst inter-Palestinian violence in two years, 6 Hamas policemen and 6 civilians were among the dead. It exposed bitter tensions in the blockaded coastal strip, where Hamas has imposed its own nationalist brand of Islam while also trying to reach out to the West to end its international isolation.
Three children died, said Hamas officials who blamed the Jund Ansar Allah and its al Qaeda-inspired leader Abdel-Latif Moussa for provoking the attack by declaring an "emirate", in a sermon on Friday.
Moussa, a middle-aged physician and local cleric, and an aide named Khaled Banat, a Syrian national of Palestinian origin, blew themselves up after killing a negotiator.