"Anything else will be met with the Israeli people's iron fist," Olmert said. "We will continue to strike with full strength, with full force until there is quiet and rearmament stops."

A few hours before Olmert spoke, a rocket hit a house in Ashkelon but caused no casualties. Olmert addressed regional mayors in the relative safety of the basement of a public building during his two-hour visit; he has toured other towns hit by rockets since the war began.

Later, he tempered his tough talk, saying: "I really hope that the efforts we are making with the Egyptians these days will ripen to a result that will enable us to end the fighting."

Ashkelon is 10 miles from the border with Gaza. The Israeli military says Hamas has Iranian-supplied rockets that can reach 25 miles into southern Israel.

Inside Gaza, an Israeli battalion commander identified only as Lt. Col. Yehuda said troops had not met significant resistance and had found several houses booby-trapped either with regular explosives, or by sealing the windows and doors and opening cooking gas valves.

"A couple of days ago, an armed squad popped up from a tunnel that was concealed by a nearby building. We took them out with tank fire and a bulldozer," he said.

In another incident, the commander said, his men spotted a suicide bomber on a bicycle.

"He ran off to take cover in a building, presumably to draw us in," Yehuda said. "We demolished the building on top of him with a bulldozer."

Brig. Gen. Eyal Eisenberg said troops were "tightening the encirclement" of Gaza City and were "constantly on the move."

The comments by Yehuda and Eisenberg were approved by Israeli military censors. They spoke to a small group of reporters who accompanied Israeli units inside Gaza. Israeli forces have not allowed journalists to enter Gaza to cover the war.

Israeli warplanes pounded suspected Hamas positions in Gaza City, and navy gunboats fired at least 25 shells. Smoke billowed over buildings.

At least 20 Palestinians died Monday, some of them from wounds suffered on previous days, Gaza health officials said.

A girl, a doctor and a Hamas militant were killed in the northern Gaza Strip, said Basim Abu Wardeh, head of Kamal Adwan hospital.

The doctor rushed to evacuate the wounded from a building where two airstrikes had taken place and was killed by a third, Abu Wardeh said. Four other medics were injured, one critically.

The Israeli military said four soldiers were injured, one seriously, in what an initial inquiry concluded was a "friendly fire" incident in northern Gaza.