Four Hamas gunmen were killed in a clash with Israeli soldiers along the Gaza border on Wednesday, further testing a shaky truce that took effect in June.

The Israeli military said in a statement that its forces had identified a group of gunmen trying to place an explosive device near the border fence, leading to an exchange of fire. Four of the gunmen were fatally hit and an Israeli soldier was lightly wounded, the statement said.

An army spokeswoman added that the military carried out two airstrikes in open areas during the confrontation, and that the soldiers had chased the gunmen, who also fired mortar rounds at the troops, inside Gaza.

Witnesses told the independent Palestinian news agency Maan that Israel had fired two missiles, one near a mosque and another near a school or homes, while fighters were in the area.

Ayman Taha, a spokesman for Hamas, the Islamist group that controls Gaza, blamed Israel for the escalation.

Both Hamas and Israeli officials have recently expressed their interest in renewing the six-month truce, which is due to expire in December. But this month it has begun to fray.

At least six Palestinian militants were killed in a clash and an Israeli airstrike on Nov. 4 after an Israeli force entered Gaza for the first time in five months to destroy a tunnel Israel said it believed was intended for use in the abduction of soldiers.

Over the following days Palestinians fired dozens of rockets and mortar shells at Israel. All landed in open areas and caused little damage. In response, Israel closed down the commercial crossings where basic goods pass into Gaza, allowing in only a limited amount of fuel on Tuesday.

Christopher Gunness, the spokesman for the United Nations Relief and Works Agency, which provides assistance to Palestinian refugees, said Tuesday that food distributions to 750,000 Gazans would come to a halt on Thursday unless the organization was able to get in wheat and other essential goods.

Peter Lerner, a military spokesman, said on Wednesday afternoon that no decision had yet been made regarding the reopening of the crossings.

In Gaza City on Wednesday, Ahmed Yousef, a senior adviser to the Hamas Foreign Ministry, denied a report that Hamas was maintaining contact with members of President-elect Barack Obama’s team and that they had met secretly prior to the American elections.

Mr. Yousef was quoted on Tuesday in Al Hayat, a London-based Arabic newspaper, saying that contact had first been made with Mr. Obama’s advisers on the Internet and that meetings were then held in Gaza. “They advised us not to reveal this information lest it influence elections or be manipulated by McCain’s campaign,” Al Hayat quoted him as saying.

Mr. Yousef said that the reporter had misunderstood him, and that he had been in contact with some Democrats to try to clarify Mr. Obama’s positions on Hamas and the Israeli-Palestinian conflict, but not with Obama team members.

With that, Mr. Yousef called on Mr. Obama to open his doors “to people with different perspectives and opinions on the conflict.” He also asked the president-elect to “act to lift the illegal Israeli siege.”