GAZA CITY, Gaza Strip ? Israeli tanks and troops moved back into southern Gaza early Thursday, closing off the entrance to a main town, residents and the military said. Three armed Palestinians were killed in airstrikes, the latest stage of Israel’s monthlong offensive.

Residents and Palestinian security officials said about 50 tanks, accompanied by bulldozers, crossed one mile into Gaza, taking up positions in a village outside the town of Rafah and at the Gaza airport, which has been out of commission for several years.

The Israeli forces advanced about five miles into Gaza, taking control of the main highway and blocking the eastern entrance of Rafah, a town on the Gaza-Egypt border, residents said. It was the farthest the Israelis have advanced in the area since the start of their offensive in late June.

As the tanks took up positions, Israeli aircraft fired missiles at three groups of militants, killing two gunmen and a security officer and wounding eight militants, security and hospital officials said. Three civilians were also wounded.

The military said Israeli forces were carrying out an operation in southern Gaza, and an aircraft fired at militants who were about to launch anti-tank rockets at Israeli forces.

Israel launched its offensive in Gaza after a June 25 cross-border raid by Hamas-linked militants who tunneled under the frontier and attacked an Israeli army post, killing two soldiers and capturing a third.

Israeli ground forces have moved in and out of several parts of the territory regularly since then, confronting armed militants, leaving considerable destruction behind. At least 119 people have been killed in Gaza since the offensive began, most of them militants.