A resurgence in factional violence in Gaza on Wednesday killed five Palestinians, including a 42-year-old woman, indicating that a fragile truce between Hamas and Fatah has collapsed.

After nightfall, warring sides in southern Gaza agreed to stop the violence, but it was unclear if this would end the clashes.

Wednesday's violence in the northern Gaza Strip began when a 25-year-old militant from President Mahmoud Abbas' Fatah party was shot and killed in the northern Gaza town of Beit Lahiya, setting off a round of gunbattles that sent rival gunmen pouring into the streets.

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Fatah officials would not comment publicly on the shooting, but privately blamed Hamas, the Islamic group that controls the Palestinian parliament and Cabinet.

A 42-year-old woman caught in the crossfire was shot in the head and later died, hospital and security officials said. Twelve other people were wounded.

Later in the afternoon, a group of gunmen ambushed Fatah-allied Palestinian security officers in the southern Gaza city of Khan Younis, blasting their police car with bullets and a rocket-propelled grenade and killing two of the officers, according to witnesses. A third officer died later of his wounds.

Fatah officials blamed Hamas militiamen for that attack, while Hamas said Fatah men had initiated the incident.

Before the ambush, the security officers stormed a house where they believed a colleague who had been kidnapped earlier in the day was being held, security officials said in a statement. Militants attacked the officers, and one was wounded, the statement said.

When two of his colleagues driving a police car tried to bring him to the hospital, they were attacked near the hospital's entrance, the statement said.

In a text message sent to reporters Wednesday evening, the Fatah leadership in Khan Younis blamed Hamas for trying to "increase chaos" in Gaza and said loyalists had now been instructed to "defend themselves by any means necessary."

After nightfall, three militant groups brought Hamas and Fatah officials in together in Khan Younis and forged an accord to remove gunmen from the streets and release kidnapped activists, according to a participant in the meeting. However, it was unclear if this would lead to a truce in the rest of the territory.

With the threats of more bloodshed, an Egyptian security delegation that has been in Gaza in recent months to mediate between the rival factions tried to restore calm, meeting with President Mahmoud Abbas Wednesday night.

The renewed surge of violence came two days after Fatah and Hamas militants carried out a series of kidnappings and engaged in gunbattles, in violation of a mid-December truce between the two groups, which are vying for control of the Palestinian government.

In December, violent clashes between them killed 17 Palestinians before the cease-fire brought the violence under control.

Also Wednesday, the French news agency AFP demanded the immediate release of one of its photographers, abducted at gunpoint in Gaza City on Monday. In a statement, AFP said there has been no word on the fate of the photographer, Jaime Razuri, 50, a citizen of Peru.

"Despite assurances from Palestinian officials that they are doing everything possible to help with the search, we are deeply concerned over Jaime's health and safety," the statement said.

In the past, most journalists and other foreigners kidnapped in Gaza have been released unharmed after a few hours. An exception was the abduction of two Fox News journalists last summer. They were held for two weeks.