GAZA CITY, Gaza Strip (AP) – Palestinian policemen went on a rampage over the killing of a colleague and seized the Gaza-Egypt border crossing for several hours Friday, forcing European monitors to flee in the latest sign of growing mayhem in the coastal strip.

A British aid worker and her parents, meanwhile, were freed late Friday, two days after gunmen seized the family in the southern Gaza Strip, Palestinian mediator Kamal Sharafi said, without giving any details of where they were released or who kidnapped them.

Friday’s border takeover and the kidnapping of the Britons fed worries that chaos in Gaza may be spreading to outsiders brought in to help develop the area following Israel’s pullout.

Gaza has experienced a wave of shootouts, kidnappings and armed takeovers of government buildings in recent months, undermining Palestinian leader Mahmoud Abbas’ efforts to impose law and order in the wake of Israel’s withdrawal from the area in September.

In new violence, a 14-year-old boy was killed Friday when a powerful Palestinian family attacked a local police station for a second straight day. Their assault the previous day caused the death of the police officer that set off the furious eruption by police Friday.

About 100 policemen stormed the Rafah border terminal in the morning, firing in the air and taking up positions at the crossing, security officials and witnesses said.

The unarmed European observers – responsible for enforcing terms of the Israeli-Palestinian agreement that opened the border last month – took refuge in a nearby Israeli military base, forcing the terminal to halt operations.

The police withdrew peacefully from the border after about three hours. Several hours later, the Europeans reopened the crossing, said Julio De La Guardia, a spokesman for the observers.

The unrest could threaten international efforts to help rehabilitate Gaza, whose economy is in tatters as it emerges from five years of heavy fighting with Israel. Under the leadership of former international envoy James Wolfensohn, donors have pledged $3 billion annually for Palestinian reconstruction projects, mostly in Gaza, for the next three years.

The Rafah terminal was opened last month under an agreement negotiated by Secretary of State Condoleezza Rice. The deal opened an important lifeline for Gaza’s economy and marked the biggest diplomatic breakthrough since the Israeli withdrawal.

Israel closed the border shortly before the pullout, fearing militants would smuggle weapons into Gaza. The presence of the EU monitors was meant to address those security concerns. The crossing cannot operate if the European contingent is not present, De La Guardia said.

The angry police officers demanded the execution of the gunman who killed the officer Thursday.

The officer and a civilian died during a shootout that erupted between two rival families outside a police station. The violence began when one of the families approached the station seeking to free a relative detained on drug charges.

Members of the incarcerated man’s family stormed the police station again Friday, sparking another shootout. A 14-year-old boy passing through the area was mistakenly shot in the head and died instantly, police said.

The freed British family was reported in good health by Jamil Sarhan, executive director of the Al-Mezan human rights group in Gaza.

The kidnapped worker for Mezan was identified as Kate Burton, 25. Her father, Hugh, a retired European Union official, and mother, Helen, were visiting her on vacation when all three were seized by armed gunmen in the town of Rafah, officials said.

There was no claim of responsibility, and Palestinian officials did not say what demands the kidnappers made.

There have been a string of kidnappings of foreign aid workers and journalists in Gaza in recent months, with gunmen usually demanding jobs, the release of relatives from prison or other favors from the government. The hostages have been released unharmed.

Abbas’ critics have accused him of giving in to kidnappers’ demands, encouraging more abductions.

Abbas has been reluctant to confront the militant groups and armed gangs, fearing it could lead to civil war. But frustration in the Palestinian public over the chaos could force him to make a move as he heads toward Jan. 25 parliamentary elections.

The Hamas militant group, running on an anti-corruption and law-and-order campaign, poses a serious election challenge to Abbas’ Fatah Party.

Hamas’ political chief said Friday that the Islamic group’s decision to run candidates in the election did not mean it was willing to end its armed struggle against Israel.

“We will enter the parliament and (engage in) political work … without giving up one inch of Palestine,” Khaled Mashaal said in a speech in Damascus, Syria, marking the 18th anniversary of the founding of Hamas.

The group has killed hundreds of Israelis in suicide bombings and seeks the destruction of the Jewish state.

A rift within Fatah between its veteran leadership and “young guard” has weakened the movement politically.

Marwan Barghouti, the imprisoned leader of the young guard, apologized Friday for the party’s failures but urged Palestinians to give it another chance in the vote.

“We do not hesitate to apologize to the Palestinian people for the mistakes that have been committed in recent years, … and I call upon the Palestinian people to renew their confidence in Fatah and to give Fatah a new opportunity,” Barghouti said in a statement from his cell.

Barghouti, who is serving a life sentence in Israel for involvement in five murders, is heading Fatah’s list of candidates for the election.

The statement, to be published Saturday in Palestinian newspapers, was obtained by The Associated Press.

AP-ES-12-30-05 1750EST