(BBC) - Four people have died in an Israeli strike on a Hamas-run police station in the southern Gaza city of Khan Younis, Palestinians say.
The Israeli military said in a statement it had targeted a rocket crew position in southern Gaza.
It said it attacked "in response to rocket and mortar attacks... on localities in southern Israel".
The strike came as Israeli Defence Minister Ehud Barak warned a "broad operation" was imminent in Gaza.
He told reporters: "Every passing day brings us closer to a broad operation in Gaza.
"We are not looking forward to it, we would be happy if circumstances prevented it."
Israel has carried out several air strikes inside Gaza in recent months in retaliation for almost daily rocket attacks on Israel by Palestinian militants.
The BBC's Aleem Maqbool in the West Bank says Israel's pressure on Hamas, or on the Gaza Strip, is not relenting.
Earlier on Tuesday an Israeli missile hit a house in northern Gaza, injuring two children.
Hamas seized control of the Gaza Strip in June, ousting its Fatah rivals.
On Monday Israel said it would reconsider plans to curb power supplies to Gaza, in retaliation for rocket attacks, after legal advice from the attorney general.
UN Secretary General Ban Ki-moon had condemned the plans as punitive.