Palestinian militants detonated a bomb targeting an Israeli army patrol along the Gaza border, the Israeli military said, in the first violence since a cease-fire went into effect more than a week ago.

Heavy gunfire was audible along the border in central Gaza and Israeli helicopters hovered in the air, firing bursts from their machine guns, Palestinian witnesses said.

The Israeli military said an explosive device exploded near the border crossing of Kissufim, targeting an Israeli patrol.

The military would not provide further details. No militant group immediately took responsibility for the attack.

An Israeli jet broke the sound barrier over Gaza City not long afterward, possibly as a warning, but there were no additional reports of Israeli retaliation.

Israel and Gaza militants have been holding their fire since Jan. 18, after Israel ended a punishing three-week offensive aimed at halting rocket fire from the territory.

Israel announced a unilateral cease-fire on Jan. 17, and that was followed by a similar announcement from Gaza militants.

Egypt is currently trying to negotiate a longer-term arrangement to allow quiet in the coastal territory of 1.4 million people, which has been ruled by the Islamic militants of Hamas since June, 2007.

The Israeli offensive killed 1,285 Palestinians, more than half of them civilians, according to records kept by the Palestinian Center for Human Rights. Thirteen Israelis, including three civilians, were also killed during the fighting.