Thousands of Palestinians deserted the northern parts of the Gaza Strip after Israel issued a warning that it is intensifying attacks on the Hamas group.
Israeli troops attacked a rocket launch facility in Gaza on Sunday in the first deployment of ground troops.
The Israeli Air Force dropped leaflets warning residents to evacuate the area prior to impending attacks on rocket-launching sites, on the sixth day of Operation Protective Edge.
Israel Defence Forces told BBC: "We do not wish to harm civilians in Gaza, but these civilians must know that remaining in close proximity to Hamas terrorists and infrastructures is extremely unsafe."
Nearly 170 Palestinians are said to have been killed since the offensive began last Tuesday.
An unnamed Israeli military spokesman told Associated Press: "During the mission a gunfight broke out, started by some terrorists operating at the site, during which four Israeli soldiers were lightly wounded.”
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The spokesman, however, declined to disclose further details on the operation.
Israel bombed three training facilities of Hamas’s military wing and buildings in Gaza city in the early hours today, according to Agence France Presse.
The UN said at least 17,000 people have taken shelter in its facilities. It urged the two countries to agree on a cease-fire soon.
A statement issued by the UN on Sunday said: "The Secretary-General, abhorring the images of Israeli families hovering in shelters in fear for their children’s safety, repeats his condemnation of Palestinian rockets fired from Gaza and demands an immediate cessation of these indecent attacks.
"The Secretary-General is also deeply worried about the impact on Palestinian families of Israeli military action."
Image: Two children stand in front of a destroyed house in Maghazi refugee camp in Center Gaza Strip. Photo: courtesy of UN / Shareef Sarhan.