More than 25 Palestinians were injured in Thursday's attacks, including an Al-Aqsa TV journalist, shot as he was covering the story.
Call for revenge
Thousands of people marched in the streets of al-Barij refugee camp on Friday and armed men fired rifles into the air, vowing revenge.
In a statement, al-Qassam Brigades said: "This blood will only increase our determination to chase the enemy and to strike it and resist by all our might until the last drop of our blood."
"The refusal by the US, EU et al to deal with Hamas reflects their disrespect for the wishes of the Palestinian people"
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A spokesman for Fatah joined Ismail Haniya of Hamas, the deposed Palestinian prime minister, in condemning what Haniya called Israel's "military escalation" and "criminal massacre" and said Palestinian fighters had the right to respond.
Emad Ghanem, a journalist working for Hamas' satellite channel Al-Aqsa TV, was filming near the al-Barij refugee camp in the east during Thursday's raid when he was hit by Israeli gunfire.
After falling to the ground, video footage showed him being hit by several more shots before fellow journalists came to his aid.
He was eventually carried off and both his legs were amputated in hospital.
An Israeli military spokeswoman said journalists were at risk if they entered a combat zone but soldiers did not deliberately target them.
A military source added that Israel did not consider a cameraman working for Hamas to be a journalist.
In a separate incident around the same incursion, Israeli soldiers fired on a rooftop where several journalists, including a Reuters camera crew, were filming. No one was injured.
Also during Thursday's raid, Azmi Abu Dalal, a Palestinian ambulance worker, said Israeli forces seized him and several colleagues when they tried to evacuate a wounded Palestinian man from a security post Hamas fighters had been using.
Abu Dalal said soldiers used them as "human shields" to exit the area.
Israeli law bans soldiers from using civilians for protection but the county has been repeatedly accused of breaching the rule.
The deaths bring to 5,776 the number of people killed since the outbreak of the second Palestinian uprising in September 2000, most of them Palestinians, according to a tally by the AFP news agency.
Israel withdrew from Gaza in 2005 after 38 years of occupation, but continues to carry out armed incursions and air strikes in the territory from where Palestinian fighters fire rockets into Israeli territory.
Source: Al Jazeera and agencies