The mayor of the West Bank city of Nablus has said he is resigning in protest at a rise in lawlessness.
The mayor's brother was killed by gunmen last year
Ghassan Shakaa accused the Palestinian Authority of failing to take action to stem rising violence in the city.
Two Palestinian militant groups, meanwhile, say they carried out the killing of an Israeli couple in the West Bank on Friday night.
The al-Aqsa Martyrs' Brigades and a Syria-based faction said they ambushed the pair near the boundary with Israel.
Mr Shakaa, an ally of Palestinian leader Yasser Arafat, said he was frustrated at seeing Nablus descend into chaos.
"I have submitted my resignation to President Arafat because I see my city collapsing and I don't want to stand idly by and watch this collapse.
"My resignation is a warning bell to the Palestinian Authority and the residents of Nablus, because both of them are doing nothing for this city," he said.
In Nablus, the power of the police has been eroded, in part by frequent Israeli raids, and gangs have proliferated.
Government officials have been kidnapped and beaten, while in November, Palestinian gunmen shot and killed Mr Shakaa's brother, Barraq.
The al-Aqsa Martyrs' Brigades and the smaller Damascus-based Popular Front for the Liberation of Palestine-General Command said they killed Eitan Kukoi, 30, and his wife Rima Novikov, 25, near the settlement of Eshkolot on Friday night.
Israeli security sources said army trackers were searching nearby Palestinian towns for the gunmen.
Earlier in the day, a Palestinian suicide bomber blew himself up near an army jeep outside the settlement of Kfar Darom in the Gaza Strip, killing himself but causing no other injuries.
In Jerusalem, Israeli police fired stun grenades at stone-throwing Palestinians at the compound known to Muslims as Haram al-Sharif and to Jews as the Temple Mount, police spokesman Gil Kleiman said.