An American peace activist has been killed as she was run over by an Israeli bulldozer in the southern Gaza Strip.
Demolition has become a regular event in Palestinian areas
Witnesses said she had been trying to stop the demolition of a Palestinian building in the Rafah refugee camp.
The woman was identified as Rachel Corrie, aged 23, from Olympia, Washington.
There were eight international protestors at the site - four American and four British - all members of a group called International Solidarity Movement.
Ms Corrie was the first member of the organisation to be killed in the conflict in the Palestinian territories.
The Israeli army said her death was a regrettable accident, but also accused the group of acting irresponsibly by intentionally placing themselves in a combat zone.
Israeli forces use tanks and bulldozers to destroy buildings near the Gaza-Egypt border, which they say are used by Palestinian gunmen to shoot at Israeli troops patrolling the area.
Groups of international protestors have gathered in several locations in the West Bank and Gaza over the last two years, trying to protect families whose homes are due to be demolished by Israeli forces.
The death occurred as the Israeli army reinforced its closure of the West Bank and Gaza Strip amid fears of attacks during a forthcoming Jewish holiday.
Palestinians will be prevented from entering Israel during the festival of Purim, which runs from Monday to Wednesday, a military statement said.
Israeli radio said the order came from Prime Minister Ariel Sharon and Defence Minister Shaul Mofaz. It added that intelligence sources had warned of attacks being planned.
Palestinian sources said that more than 10,000 workers from Gaza had been prevented from going to work in Israel on Sunday morning.
Bush's 'road map'
The Israeli army said it had continued its security operations, arresting many suspected Palestinian militants over the weekend.
No date was given for the ending of restrictions, but international routes for people and goods would remain open, the army said.
The decision to tighten security came a day after President Bush promised to publish a new peace "road map" soon.
Mr Bush said the proposals - which include the establishment of a Palestinian state within a set timeframe - would be announced once the Palestinians had a prime minister with "real authority".
He said any Palestinian state must be "a reformed and peaceful and democratic state that abandons forever the use of terror".
But he also said Israel should bring an end to the building of new settlements in the occupied territories.
Mr Sharon's administration publicly welcomed Mr Bush's statement, but correspondents say that privately, officials will be concerned at the apparent move towards the European standpoint which encourages more pressure on Israel.
An estimated 753 Israelis have been killed since the beginning of the Palestinian uprising in September 2000, according to official figures.
More than 2,000 Palestinians have died in the same cycle of violence.