Israeli forces have killed at least 17 people in Gaza on one of the deadliest days for months in the territory.
Beit Hanoun has been the centre of a three-day Israeli raid
Palestinian doctors said seven people died in Israeli raids which came hours after a crowd of women went to the aid of gunmen being besieged in a mosque.
At least two women were killed as Israeli troops opened fire at the mosque in the town of Beit Hanoun.
Hamas leader Ismail Haniya praised the women but Israel said they had served as "human shields" for the militants.
An Israeli military spokesman said five air strikes had taken place after dark on Friday, targeting the towns of Beit Hanoun, Beit Lahiya, Jabaliya and Rafah.
Israeli officials say they were targeting suspected Palestinian militants who were planting explosives or who had carried out rocket attacks.
Israeli forces entered Beit Hanoun on Wednesday in what they said was a mission to stop rocket attacks.
In the dramatic mosque rescue, Hamas radio issued an appeal to local women when a tense stand-off developed between Israeli forces surrounding the building and up to 15 militants who had taken refuge inside.
One of the women, Nahed Abou Harbiya, described what happened to the BBC Arabic Service.
"All the women headed to the mosque to get the Palestinian resistance men... But the Israeli occupation forces were firing heavily at us with their machine guns and also threw stun grenades at us.
"We entered the mosque and indeed we got all the resistance men out and put female attire on them so that the Israeli occupation forces wouldn't arrest them," she said.
Shots were fired as the women approached Israeli forces. As some of the women tried to pass the troops, further shots came and two women fell to the ground.
At least 10 women and a Palestinian cameraman were injured.
"We risked our lives to free our sons," Um Mohammed, a woman in her 40s, told the AFP news agency afterwards.
Hamas radio reported that all of the militants in the mosque escaped and were uninjured.
Israeli military spokeswoman Avital Leibovich said: "We saw crowds of women. Behind the women hid some of the militants. Some of them were even dressed up as women: we have footage," she said.
"Unfortunately because the militants shot at our forces, sometimes we had to respond."
The BBC's Matthew Price in Jerusalem says that in television footage of the incident, some men are visible in the crowd, but there is no evidence that they were carrying guns.
Palestinian Prime Minister Ismail Haniya, of Hamas, said the event was part of a "planned annihilation" of the Palestinians.
He called on UN Secretary General Kofi Annan to come to see what he described as "massacres" committed against them.
About 30 Palestinians and an Israeli soldier have died in violence since the Israeli operation in Beit Hanoun began on Wednesday. Many of those killed were gunmen, but a four-year-old boy died from his wounds overnight.
BBC Middle East analyst Roger Hardy says that Israel's most immediate aim is to prevent rocket attacks against its territory, but beyond that it wants to strike a decisive blow at Hamas.
Israeli forces have made regular incursions into Gaza and the West Bank following the capture of an Israeli soldier, Cpl Gilad Shalit, in a cross-border raid by Palestinian militants on 25 June.
More than 300 Palestinians have been killed in army operations since then, according to Israeli human rights group B'Tselem.