Beit Hanoun, Gaza Strip ? Responding to rocket fire, Israeli troops and tanks swept through three Palestinian towns and the outskirts of a refugee camp Wednesday in the biggest operation in the Gaza Strip since violence broke out nearly 17 months ago. Five Palestinians, including a civilian, were killed in exchanges of fire that began before dawn.

Islamic militants said they will keep firing rockets at Israel, despite Israeli warnings that such attacks will trigger more large-scale operations.

In the West Bank, there were exchanges of fire after two Israeli tanks and several other vehicles entered the town of Jenin, Palestinians said. The Israeli military spokesman’s office said it had no knowledge of an incursion in Jenin.

In a clash late Wednesday with Israeli soldiers near a Jewish settlement in Gaza, a Palestinian gunman was killed and three others escaped, Israel Radio reported. The moves came amid increasing tension within the Palestinian Authority and exasperation in Israel, whose persistent military efforts have failed to prevent the Palestinians from using an ever-expanding arsenal of weapons including the Qassam-2 rocket, which puts Israeli cities within range.

After nightfall, Israeli forces were pulling out of Beit Hanoun, a town in the northeast corner of the Gaza Strip. They left Beit Lahiya, a small part of the nearby Jebalya refugee camp and Dir al-Balah, a town in central Gaza, several hours after entering.

However, Palestinians said a line of tanks was approaching Dir al-Balah again late Wednesday.

Palestinians in Beit Hanoun described an unusual scene: Israeli tanks firing at rock-throwing Palestinian teen-agers near buildings draped with banners in Arabic and English that read, “Better have pains of peace than agonies of war” Â a quote from Yitzhak Rabin, the Israeli prime minister who nine years ago signed Israel’s first interim peace accord with the Palestinians.

Israeli Cabinet Minister Ephraim Sneh said the operation would continue for several days, until rocket factories were found, and warned of more large-scale, long-term raids if rocket fire persists. “This is a threat we cannot tolerate,” he said.