The clashes came as the two main factions of the ruling Fatah Party — the so-called "young" and "old" guards — announced an end to an internal rift that threatened to bolster the electoral prospects of Hamas militants. Young guard members announced that Fatah will submit a single, unified list for the elections.
After intense negotiations, the two sides came together just two hours before a Wednesday afternoon deadline for submitting the list.
"We affirm here that we are going to this election with one list. We are going to elections unified in Fatah to achieve a victory," said senior Palestinian official Mohammed Dahlan, a leader of the young guard.
In other developments:
In Gaza City on Wednesday, more than 60 gunmen stormed the main election office, exchanging fire with some 500 security forces who rushed to the scene, surrounding the building and setting up roadblocks. One policeman was wounded in the leg by gunfire and whisked away in an ambulance.
In Rafah, gunmen surrounded the election office, but Palestinian police prevented them from entering. In Khan Younis and Deir el-Balah, gunmen made it into the buildings.
All the standoffs ended within hours with the gunmen leaving the scene.
Such activity by gunmen has become increasingly common in the West Bank and Gaza in recent months, underscoring growing lawlessness in the Palestinian territories. Wednesday's violence highlighted the rising chaos within Fatah itself, adding the demands for participation of the Fatah-affiliated Al Aqsa Martyrs Brigades to an already volatile mix of competing interests.
The Palestinian Interior Ministry condemned the mayhem, saying in a statement that attempts to take over election offices are "national crimes."
An Al Aqsa Martyrs' Brigades leader in Khan Younis, Abu Zakariya al Assouili, said his group tried to contact Abbas to push for greater participation in the party list but to no avail.
"We're objecting to a Palestinian election that does not represent a Palestinian vision," he told The Associated Press. "We want the base to dictate our fate, not America or Israel."
Dahlan predicted that Wednesday's healing of the Fatah rift would augur well for stability in the Palestinian territories.
"Now Fatah is unified in one list and its Ministry of Interior has the responsibility of implementing law and stopping chaos," he said.
Fatah has been bitterly divided between party veterans and a young generation of activists — led by jailed uprising leader Marwan Barghouti — demanding a bigger role in party decision-making. Two weeks ago, the young guard broke off from the party to protest Fatah's slate of candidates and submitted its own list. Eager to bring the young guard back, Abbas agreed to redraw the party's list of candidates, giving top positions to younger activists.
Last-minute differences threatened to revive the split, with both veterans and young guard activists threatening to break away unless their candidates featured prominently on the voting list. Analysts said a divided Fatah could enable Hamas, the militant group opposed to the existence of a Jewish state, to win the Jan. 25 vote.
Dahlan said the agreement reached Wednesday puts Barghouti at the top of a unified Fatah list.
Israel's recent withdrawal from Gaza has enabled militants to reach rocket-launching grounds closer to Israel, bringing Israeli towns such as Ashkelon within rocket range.
"Anyone who will not heed to this warning is placing his/her life in immediate danger," the Israeli leaflet states. "Know that the terror organizations have turned you into hostages and human shields and are harming your interests."
"We are definitely stepping up the level in our response," said army spokeswoman Maj. Avital Leibowich. "We can't allow the situation to carry on like this. We can't endanger the lives of our people."
Palestinian negotiator Saeb Erekat condemned the Israeli plans.
"This is tantamount to reoccupying Gaza," he said. "We condemn this because it will add to the problem rather than solving it."