Israeli troops killed four armed Palestinians in a gunbattle on the Gaza border on Wednesday that rattled a nearly five-month lull, the Israeli army and Palestinian medics said.
"Four militants were killed and were transferred to Nasser Hospital" in the south of the Gaza Strip, a medic said.
Witnesses said the militants were from the Hamas movement which controls the Gaza Strip.
An Israeli army spokeswoman said: "Troops identified hitting the four Palestinians and later found firearms and grenades on their bodies."
The gunbattle broke out after Israeli armoured vehicles crossed into the Hamas-controlled territory near the city of Khan Yunis, Palestinian witnesses and security officials said.
The army said mortar rounds were fired into Israel and that it responded with two air strikes just inside Gaza.