Palestinian militants have shelled a Jewish settlement in the Gaza Strip, killing a woman and injuring another, the Israeli military has said.
The homes of Gaza settlers are heavily guarded
A mortar landed on the woman's house in the Neve Dekalim settlement in southern Gaza, according to an army spokesman.
Israeli tanks responded by firing on the nearby Palestinian town of Khan Yunis, injuring two, residents said.
The violence came as Israeli forces went on high alert for the Jewish Yom Kippur holy day which begins at sunset.
Four mortars landed on Neve Dekalim. One landed directly on a house.
Two women inside were injured and one later died of her wounds in hospital.
Both the Islamic Jihad and Hamas militant groups have said they carried out the attack, AFP new agency reports.
Gaza's settlers live in neat bungalows and villas surrounded by trees, gardens and pools, but their perimeters are heavily guarded by the Israeli army.
For the more than a million Palestinians in Gaza, the 8,000 or so settlers, who take up a third of the land, are a hated symbol of the Israeli occupation and militants regard them as legitimate targets, says the BBC's Gaza correspondent Alan Johnston.
Hundreds of rockets and mortars have been fired on settlements during the past four years of violence, but this is believed to have been only the second time someone has been killed in such an attack.
On Thursday, three Israeli soldiers were killed in an attack by Palestinian militants on another Gaza settlement, Morag.
The militants who had infiltrated the settlement were then shot dead by Israeli troops.
The attacks have further fuelled anger among some settlers over plans by Israeli Prime Minister Ariel Sharon, to pull them out of the Gaza Strip and four enclaves in the West Bank.
As Israel prepares to mark Yom Kippur - the Day of Atonement - Israeli Defence Minister Shaul Mofaz ordered the army to tighten the closure on the West Bank and Gaza Strip.
Security guards and police have also been deployed in and around cities.