A British human rights worker and her visiting parents were kidnapped in the Gaza Strip today.
The 25-year-old woman is understood to have been showing her mother and father around the town of Rafah when they were snatched by an armed gang.
It was reported that the woman worked at the Al Mezan Center for Human Rights.
There was no immediate claim of responsibility for the kidnapping. Palestinian police said the kidnappers' car was spotted heading north. Several foreigners have been briefly abducted in Gaza in recent months, usually for ransom.
Meanwhile, at least three explosions were heard in the northern Gaza Strip this evening minutes after Israel declared that it was enforcing a new "no-go zone" to prevent cross-border rocket fire from the area, residents said.
Palestinians have condemned the new buffer zone, saying it was tantamount to re-occupying land Israel gave up in September when troops quit Gaza after 38 years of occupation.
"Israel has left the Gaza Strip and has no right to come back," President Mahmoud Abbas told reporters in Gaza. "They should not make any pretext."
Earlier, gunmen from the ruling Palestinian movement Fatah traded fire with police and shut election offices in the Gaza Strip in a new challenge to President Mahmoud Abbas ahead of next month's election.
The gunmen demanded changes to the latest proposed list of election candidates, which was due to be submitted by Mr Abbas today as a way to patch up a damaging split between Fatah veterans and younger rivals.
The internal Palestinian squabbles, clashes with Israel, and the prospect of Israel's own elections early next year have stalled any hopes of peacemaking in the near future.
The growing violence has driven some officials to urge Mr Abbas to postpone the election, in which Hamas Islamic militants stand to benefit from the confusion within long-dominant Fatah.
Gunmen from Fatah's al-Aqsa Martyrs Brigades exchanged fire with police in two separate firefights. One policeman was wounded before the militants were driven off. Tense police, masked like the gunmen, patrolled near election offices.
Elsewhere, al-Aqsa fighters forced at least three offices to close, though the electoral commission said work was resuming in some places after police restored order.
In order to face the challenge from Hamas, a breakaway faction of the Fatah young guard announced formally that it was reuniting with Mr Abbas's mainstream to present a single list of election candidates. The list is to be headed by uprising leader Marwan Barghouthi, jailed by Israel for a role in militant attacks.
The election is crucial for Mr Abbas to establish his authority and implement his agenda of talks with Israel and internal reform. He hopes to bring Hamas on board through the ballot and then persuade them to put aside their weapons.
At meetings in Gaza yesterday, Mr Abbas tried to get militant leaders to agree to halt cross-border rocket fire and renew their pledge to follow a ceasefire that brought 10 months of relative calm.
But a leader of Islamic Jihad, which has carried out suicide bombings despite the truce and fired regular rocket salvoes, said he did not believe there would be a ceasefire extension. "When the time is up there will be a general position, but calm will most likely not be extended," said Khaled al-Batsh.
Hamas has suggested its comparative restraint could end if elections are not held on time. The most recent flare-up has been concentrated around northern Gaza, from where militants have fired rockets into Israel in what they call retaliation for raids in the occupied West Bank as well as strikes on Gaza.
Israeli aircraft fired missiles into the Gaza Strip early today and the army said it had targeted three routes used by militants firing rockets. There were no reports of casualties.