The EU's new foreign policy chief has been in Gaza on one of the highest level visits there by a Western official since Hamas took power.
Baroness Ashton's trip comes amid a new push by the EU and US to revive stalled Middle East peace talks.
The international quartet of Middle East mediators - the EU, US, UN and Russia - is to meet in Moscow later.
As Lady Ashton arrived, militants in Gaza fired a rocket into Israel, killing a man, Israeli officials said.
The rocket struck the Netiv Ha'assera kibbutz in southern Israel killing a foreign agricultural worker, according to reports.
Jon Donnison BBC News, Gaza
Baroness Ashton's convoy of armoured cars blazed an isolated trail as it swept through the Erez Crossing into Gaza. Once she got here though, she soon had company: a huge media scrum at the United Nations Food distribution centre reflecting the rarity of such a visit by a senior Western political figure. Dwarfed by burly security guards, she was jostled past the sacks of food aid.
Even as she spoke to the press, there was a reminder that things often don't go to plan in the Middle East. In southern Israel, a Thai farm worker was killed by a rocket fired by militants in Gaza - a reminder of why Israel says the blockade is necessary and a distraction from the baroness's main focus, which is the humanitarian situation in Gaza.
Baroness Ashton was only in Gaza for a few hours. From here, she will head to a Middle East quartet meeting in Russia. Few Gazans will expect her visit to really change anything, but she will at least be able to say she has first-hand experience of a place at the heart of the Middle East conflict.
Although militants in Gaza have fired hundreds of rockets into Israel, this is the first fatality since the end of Israel's offensive there in January 2009.
Baroness Ashton said after the attack: "I condemn any kind of violence. We have got to find a peaceful solution to the issues and problems... we need to move forward."
Baroness Ashton will later join US Secretary of State Hillary Clinton, who has already arrived in the Russian capital for the talks.
The Moscow meeting will "demonstrate international support" for indirect talks between Israel and the Palestinians, said US State Department spokesman PJ Crowley.
Baroness Ashton swept into Gaza City from Israel in a convoy of armoured cars and was taken to a UN food distribution centre.
The BBC's Jon Donnison in Gaza says she is not expected to meet Hamas leaders during her brief visit.
The EU is the largest contributor of aid to the Palestinians, delivering 1bn euros ($1.4bn; £890m) a year.
'Need for aid'
Baroness Ashton told the BBC there was "a need to get aid through" to Gaza.
Has a degree in economics from the University of London
Awarded a life peerage by former UK Prime Minister Tony Blair in 1999
Made leader of UK upper house, the House of Lords, by Gordon Brown in 2007
Became EU Trade Commissioner in 2008
First High Representative for Foreign Affairs and Security Policy in enlarged EU
Only two European foreign ministers have come to Gaza in the past year, our correspondent notes.
Foreign officials are often refused entry by Israel, or their governments choose not to come because they do not recognise Hamas.
The visit has been welcomed by the United Nations, which says the blockade of Gaza has left hundreds of thousands in Gaza living in poverty.
The head of the UN's refugee agency for Palestinians (UNRWA) in the Gaza Strip, John Ging, said the people of Gaza were hoping for a single outcome from Baroness Ashton's visit - a lifting of the Israeli siege.
"We have to have action. A thousand days and a thousand nights of a medieval siege is far too much. It's a shame - it's a disgrace," he said.
Baroness Ashton has been criticised as too inexperienced for the new job of EU High Representative, a post created by the EU's Lisbon Treaty.
Her visit comes as the US and Israel try to bridge divisions over Israeli plans for new building in occupied East Jerusalem.
The Palestinians have pulled out of indirect talks because of the plan.
Israel's building announcement has provoked fresh violence in East Jerusalem and the West Bank.
Mrs Clinton has described the announcement - made while US Vice-President Joe Biden was in Israel last week - as "insulting".
She has made a series of demands of Mr Netanyahu - on the housing project and on showing his commitment to peace talks.
The Gaza Strip has been under an Israeli blockade since 2007, when the Islamist movement Hamas took power.
In 2008 Israel launched a three-week offensive against Gaza which killed more than 1,000 Palestinians and caused widespread damage to its infrastructure.
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