Israeli troops, backed by tanks, crossed the border into Gaza early on Thursday and continued to exchange fire with Palestinian fighters in the eastern part of the refugee camps as night fell.
Palestinian fighters said they shot back at Israeli troops with rocket-propelled grenades and mortars.
An Israeli military spokeswoman said Israeli aircraft attacked several Palestinian fighters who came close to troops during the raid.
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Emad Ghanem, a journalist working for Hamas' satellite channel Al-Aqsa TV, was filming near the al-Barij refugee camp in the east when he was hit by Israeli gunfire.
As he lay on the ground, video footage appeared to show him being hit by several more shots before fellow journalists came to his aid.
He was eventually carried off and had both his legs 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.
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 protecition.
An Israeli military spokesman said: "After conducting a preliminary examination, we know nothing about such an incident".
An Israeli military spokeswoman said Thursday's raid was a "routine operation", about a kilometre inside Gaza, to locate Palestinian fighters.
Nour Odeh, Al Jazeera's correspondent in Gaza, said: "Israel has given itself the right to maintain military operations within a certain distance from the border in the Gaza Strip, even two years after it said it completely left the [it].
"... That's why the Israeli military considers entry the peripheries of al-Barij refugee camp a routine operation."
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.