Israel stepped up its month long offensive against militants in the Gaza Strip Friday, conducting house-to-house searches and attacking Palestinian sites with air strikes and tank shells, officials said.

Three Palestinians, including two Hamas members were killed before dawn Friday and two others were killed just after midnight in an Israeli airstike on the southern town of Rafah.

The two dead were a woman in her 60s and her son, said Dr. Ali Musa, the director of the local hospital. Five other people, all civilians, were seriously wounded, he said.

The Israeli army said its aircraft fired at several armed Palestinians.

Musa said the missiles hit the house of a family as they were trying to flee the area as Israeli ground forces came closer. Palestinian security officials said Israeli troops and tanks had moved to the eastern edge of Rafah.

Friday's pre-dawn searches came a day after dozens of Israeli tanks rolled into Gaza, and Israeli forces killed eight Palestinians in clashes and air attacks. One of the casualties was an 8-year-old boy, Palestinian officials said.

Three Palestinians were killed by Israeli fire in two separate incidents before daybreak Friday, hospital officials said. The Hamas militant organization said two of the casualties were Hamas members.

The Israeli army said in a statement its forces targeted 25 gunmen carrying anti-tank missiles who were planting explosives in the army's area of operations. It didn't mention casualties.

Israeli aircraft also hit two houses in Gaza City with missiles. Residents said the military warned occupants to leave before the attacks, and no one was hurt.

Also Friday, Palestinian and Israeli officials and European monitors agreed to reopen the Gaza-Egypt border crossing on Saturday and Sunday for one-way traffic into Egypt, said Palestinian negotiator Saeb Erekat.

The crossing was intended for students to return to schools, for businessmen and for humanitarian cases, he said.

It would be the second time since the latest fighting erupted in Gaza June 25 that the terminal would be opened, but the previous time was for Palestinians returning home from Egypt. Earlier agreements to reopen the crossing from Gaza to Egypt broke down at the last minute.

Israel, which has been criticized for creating a humanitarian crisis in Gaza, said it opened another border checkpoint to allow 160 truckloads of food and medical supplies into Gaza, as well as gasoline and diesel.

The United Nations said Thursday it was concerned that "with international attention focusing on Lebanon, the tragedy in Gaza is being forgotten." It called on both Israel and the Palestinian militants to recognize their obligations to protect civilians during hostilities, but singled out Israel for criticism.

The U.N. said Israel fired an average of 200-250 artillery shells per day into Gaza, and has killed 175 Palestinians since fighting began more than a month ago. The statement also called on Palestinian militants, who fire an average of 8-9 rockets into Israel each day, to stop.

Fighting on two fronts Thursday, against Islamic militants in Gaza and against Hezbollah guerrillas in southern Lebanon, Israel had one of its heaviest days of fighting since Hamas-linked militants captured a soldier from an Israeli army post near the Gaza frontier more than a month ago.

As the tanks took up positions, Israeli aircraft fired missiles at groups of gunmen, killing four. The strikes wounded 26 Palestinians, at least 10 of them militants, security and hospital officials said.

Forces later fired a tank shell at residents gathering in the area after daybreak, killing an 8-year-old boy and wounding three people, including a 4-year-old girl, hospital and security officials said. The bodies of three more dead people were brought to the hospital early Thursday, but they were not believed to be militants, medics said.

Israel launched its Gaza offensive after a June 25 cross-border raid by Hamas-linked militants who tunneled into Israel and attacked an army post, killing two soldiers and capturing a third. Israel has demanded the release of the soldier and an end to the firing of homemade rockets at Israel by Gaza militants.

Israeli ground forces have moved in and out of several parts of the territory regularly since then, confronting armed militants and leaving behind considerable destruction.