Four members of militant Palestinian group Islamic Jihad have been killed by an Israeli air strike in the northern Gaza Strip, the group said.
Israel is launching air raids following Palestinian rocket attacks
Israel's army said it had carried out the air strike in Jabaliya refugee camp but did not give any further details.
The attack came after Israel threatened to step up raids on Gaza militants accused of firing rockets into Israel.
Earlier, Israeli missiles killed a Hamas militant and damaged what Israel called a weapons workshop.
Israeli air strikes have killed more than 30 people in the last week, several of them civilians, as rocket attacks from Gaza have continued.
'In the crosshairs'
On Sunday, Israeli Prime Minister Ehud Olmert threatened to step up military operations aimed at militants in Gaza in response to recent rocket attacks against Israel.
"If the measured steps we are taking, in the political and military sphere, do not bring about the desired calm, we will be forced to intensify our response," Mr Olmert said at the cabinet meeting.
Hamas and Islamic Jihad would be the first targets for any "sharper" Israeli action, the cabinet decided.
Israeli National Infrastructure Minister Binyamin Ben-Eliezer told Israel Radio that all Hamas leaders with any involvement in rocket attacks should be targeted.
"I don't distinguish between those who carry out the attacks and those who give the orders. I say we have to put them all in the crosshairs," Mr Ben-Eliezer said.
On Sunday, at least eight people died in an Israeli air strike said to be on the home of Khalil al-Hayya, a lawmaker from the Palestinian militant group Hamas. He was not there at the time.
The Israeli military confirmed there had been an air strike in northern Gaza on Sunday evening, but said it was aimed at a group of armed militants gathered outside a house.
However, reports from Gaza City suggested the attack did strike Mr al-Hayya's home, and that several members of his family were among those killed.
Shortly after the air strike, Mr al-Hayya visited Gaza City's Shifa hospital, where those wounded were being treated.
"We will go ahead despite the challenges, despite the martyrs, despite the pain that I am suffering and my people are suffering," he told reporters.
A Hamas spokesman, Fawzi Barhoum, said those killed were civilian members of Khalil al-Hayya's family.
The Israeli strikes came as Palestinian factions Hamas and Fatah appeared to be holding to a truce that ended days of bitter civil fighting on the streets of Gaza.
The truce, which came into effect on Saturday afternoon, is the fifth such pact since violence broke out the previous Sunday.
Since then, about 50 people have died in clashes between the two groups.