Israeli troops, tanks and attack helicopters were back inside the Gaza Strip again Sunday, firing missiles and exchanging gunfire with militants, signaling that the large-scale operation that began after a soldier was captured last month is still in full swing.

Israeli tanks and armored personnel carriers approached the town of Beit Hanoun in northern Gaza early Sunday, residents and Palestinian security officials said, as attack helicopters fired machine guns to clear the area of militants.

Before daybreak, an Israeli aircraft fired a missile at a group of gunmen, Palestinians said. As ambulances approached, another missile was fired to keep them away, they said.

Palestinian hospital officials said seven people — three gunmen and four civilians, including a 4-year-old boy — were wounded in other missile strikes in Beit Hanoun. A missile knocked out electricity in northern Gaza, residents said.

Armed Palestinians exchanged fire with Israeli forces, and militants said they set off a land mine next to an Israeli bulldozer building embankments near the residential areas of the town. Hamas said its cells activated bombs against several Israeli bulldozers and tanks.

The Israeli forces were operating in the northeastern corner of Gaza, opposite the Israeli town of Sderot, a frequent target of Palestinian rockets.

The Israeli military said Israeli forces operating in the area fired at a group of militants and a Hamas office.

Israel started its offensive in Gaza on June 28, three days after Hamas-backed militants tunneled under the border and attacked an Israeli army post, killing two soldiers and capturing a third.

Israel has declared two goals for its Gaza offensive — winning release of the soldier, Cpl. Gilad Shalit, and ending Palestinian rocket fire at Israeli communities around Gaza. Two rockets reached as far as the city of Ashkelon, 7 miles northeast of Gaza.

Ten days ago Israeli forces carried out a two-day sweep of northern Gaza, entering Beit Hanoun and another town, Beit Lahiya, looking for militants and leaving behind a swath of destruction. Israeli forces earlier moved into the southeastern corner of Gaza, and after the first operation was completed in the north, Israel sent tanks and troops into another sector of southern Gaza. By Saturday, however, all Israeli ground forces were out of the territory.

However, airstrikes continued unabated. On Saturday, Israeli aircraft struck four targets, killing two Palestinians. The targets were the Palestinian Economics Ministry in Gaza City, a bridge in the south, a Hamas weapons workshop and a group militants preparing to fire rockets at Israel, the military said.

Witnesses and Palestinian security said the new land operation in northern Gaza started Saturday evening with machine gun and shell fire, then about 10 tanks and bulldozers crossed into Gaza, with dozens of other armored vehicles poised just inside Israel. Palestinian hospital officials said two people were wounded by Israeli shells.

An AP reporter in Gaza City heard an Israeli broadcast on a radio frequency usually used by a Hamas station calling on residents to stay out of the way of the fighting. "We are not gong to stop op in Gaza until the terrorist hand over the soldier Gilad Shalit," said the broadcaster, apparently an Israeli soldier, in broken Arabic.