Shortly after dawn this morning, tanks from the Israeli Defence Force entered Khan Younis in southern Gaza. It is the biggest settlement in the region and a stronghold of Hamas.
It came after fierce fighting broke out for the first time overnight on the northern outskirts of Gaza City.
There were loud explosions and heavy gunfire as night fell and Hamas-linked militants engaged Israeli soldiers at close range in the Shujaiya district.
Hamas has told the residents of Gaza that they are on course for victory over Israel.
Meanwhile, Israel has confirmed that three of its soldiers have been accidentally killed by tank fire from their own side.
Israel has said the aim of its offensive is to crush the militants who fire rockets into towns over the Israeli border. Military sources say 20 such missiles were fired yesterday.
In addition, medical officials in Gaza say the majority of the casualties they treat are civilians.
It is claimed more than 500 people have been killed and 2,500 wounded since the Israeli attack began 10 days ago.
Four Israeli soldiers have died, along with four civilians.