Israeli troops have shot dead two Palestinian gunmen during a confrontation in the southern Gaza Strip.
Media reports say the violence occurred on Sunday at an airport where Israeli forces have been deployed since invading Gaza last week in a bid to free a captured soldier.
Meanwhile, Hamas's armed wing has threatened to attack schools and other infrastructure facilities in Israel if the Gaza offensive continues.
A spokesman said Hamas will strike targets in Israel it has not yet attacked. He said Israel will be dragged into what he called a "sea of blood" if the offensive continues.
Earlier on Sunday, Israeli warplanes attacked the empty Gaza office of Palestinian Prime Minister Ismail Haniyeh. Palestinian President Mahmoud Abbas denounced the airstrike, calling it a "criminal act."
Israeli Prime Minister Ehud Olmert has said no one is immune from the Israeli offensive.
Israel holds Hamas responsible for the kidnapping and has launched airstrikes against Gaza targets to pressure militants into freeing the soldier. A least one Hamas militant was killed in a missile attack earlier today.
Militants from the armed wing of Hamas and two other groups, the Popular Resistance Committees and the Army of Islam have offered to release the soldier if Israel stops its Gaza assault and releases one thousand prisoners. Israel has rejected the demand.
In other news, Israel re-opened its main cargo crossing into Gaza to allow fuel and other supplies to be sent to the impoverished region.