Jerusalem ? Israeli forces cut main Gaza roads on Thursday after militants fired rockets at an Israeli town, and soldiers tore down houses in a refugee camp on the Egyptian border.

The Israelis have been unable to stop rocket fire into Israel, despite frequent army operations in northern Gaza, the launching zone. On Thursday, Israeli helicopters fired missiles at the area as a warning, Army Radio reported.

Prime Minister Ariel Sharon intends to pull Israeli soldiers and settlers out of Gaza next year. Critics warn that that after the exit, rocket attacks will intensify.

Militants are increasing attacks to portray the pullout as a defeat, while Israel has carried out tough crackdowns to show it’s leaving of its own volition.

Palestinians on Thursday fired two of the primitive homemade Qassam rockets at Sderot, an Israeli town of about 20,000 less than a mile from the Gaza fence.

One rocket hit a storage shack next to a house, and the other landed in a field. No one was hurt.

Also, Palestinians fired several mortar shells at a Jewish settlement in Gaza, the military said. No damage or casualties were reported.

Responding to the rocket fire, Israel placed roadblocks on main highways, dividing Gaza into three sections between which no one was allowed to travel.

Cutting Gaza into three parts, a frequent response to violence, is seen by Palestinians as collective punishment, though the Israelis claim the purpose is to keep militants from transferring weapons from one part to the other.

In southern Gaza on Thursday, Israeli forces knocked down houses in the Rafah refugee camp on the Egyptian border.

The Israeli military said an operation was underway against the “terrorist infrastructure” in the camp, and two abandoned structures used by militants to fire mortars and guns were destroyed.

Associated Press pictures showed residents picking through rubble strewn with broken furniture and torn clothes.

The camp is a frequent target as Israeli forces search for arms smuggling tunnels, some of which terminate under buildings in the camp. Hundreds of structures have been destroyed in the camp during the current conflict.

In the Rafah camp after nightfall, an explosion rocked the house of a well-known Islamic Jihad militant, Mohammed Khalil, who was injured along with three other people, Palestinians said. There was no immediate word on what caused the blast. The Israeli military had no comment.

A second blast occurred in a house in the Shajiea neighborhood, east of Gaza City, killing Fahdi Iomear of the Al Aqsa Martyrs’ Brigades, Palestinian officials said. The officials said the explosion was caused by an explosive device. They did not elaborate.

There have been no effective measures by Palestinian authorities to stop the rocket and mortar fire, though from time to time residents have chased militants away for fear that using their land as a launching pad would lead to Israeli retaliation.

Israeli efforts have been equally ineffective. After two Israelis, including a child, were killed in Sderot in late June — the only fatalities from the rocket fire in four years of violence — Israel sent troops into northern Gaza, flattening farmland and controlling territory for six weeks before withdrawing.