RAFAH, Egypt — Egyptian guards with riot shields formed human chains along the Egypt-Gaza border today, but were unable to stop hundreds of Palestinian Arabs from rushing into Egypt after a bulldozer wrecked another section of fence along the frontier.

Men in black clothing, some of them masked, stood atop the bulldozer as it knocked down a concrete slab under the watchful eyes of Egyptian forces on the other side who shot in the air in an attempt to hinder the flow of Gazans into Egypt.

Thousands of Palestinian Arabs, many of them carrying empty fuel canisters, managed to push through several openings despite the presence of the Egyptians deployed nine rows deep in some places. At one point, guards aimed a water cannon above the heads of people, not at them, to keep them back.

Cranes were positioned next to the border, lifting crates of supplies over into Gaza.

Egyptian forces took up positions a few steps into Palestinian Arab territory, using shields to protect themselves from some Gazans who climbed atop car roofs and threw stones at them. Witnesses said a photographer was lightly injured in the clash.

The border was first breached Wednesday, when Palestinian Arab militants blew down large sections of the border wall. Since then, Egypt has allowed tens of thousands of Palestinian Arabs to go back and forth, but has rejected any suggestion of assuming responsibility for the crowded, impoverished territory.

The visitors included a gaggle of Palestinian Arab women in finely embroidered dresses and fresh makeup, heading to relatives’ weddings in Egypt they said had been hastily moved up to allow Gazan family members to attend.

Yousef Mohammed, 17, from Gaza, said he waited until today to make the trip because he was trying to get together enough money first to shop in Egypt. “They don’t want us to go in,” he said, pointing at the riot police.

Travelers returning from Egypt said they heard loudspeaker announcements there that Gazans had to return home by 7 p.m. today.

The border issue became a verbal spat between Egypt and Israel when Deputy Defense Minister Matan Vilnai of Israel said Israel gradually wants to relinquish responsibility for Gaza, now that its border with Egypt was blown open.

It was a position echoed by other Israeli officials, who said the border breach could pave the way for increasingly disconnecting from the territory.

However, Defense Minister Ehud Barak of Israel, speaking yesterday on the sidelines of the World Economic Forum in Switzerland, said he did not want to “go too far in my interpretation of this.”

Egypt angrily rejected the Israeli ideas and said it would not change border arrangements.

In an interview published today in the weekly Al-Osboa, President Mubarak called the situation in Gaza “unacceptable” and called on Israel to “lift its siege” and “solve the problem.”

The opening of the border, even if temporary, provided a significant popularity boost to Gaza’s Hamas rulers, who can claim they successfully broke through the internationally supported Israeli closure that has deprived the coastal strip of normal trade and commerce for nearly two years.

Both Egypt and Israel restricted the movement of people and goods in and out of Gaza after Hamas won parliament elections in 2006, and further tightened the closure after Hamas seized control of the area by force last June.

A handful of black-clad Hamas gunmen fanned out along the Gaza side of the border today, attempting to create order amid waves of Gaza residents approaching the area. It was the first time since the border fence was torn down that Hamas deployed uniformed men to deal with the chaos. The militant group has been using plainclothes agents to regulate the crowd.

Warning that militants were among the Palestinian Arabs who entered Egypt, the Israeli military raised its level of alert yesterday, fearing an attack on Israel, and closed the highway along the Israel-Egypt border.

Overnight, Israeli air strikes killed four Hamas militants around Rafah, Palestinian Arab and Israeli officials said today.

Two Hamas militiamen were killed as they drove near the shattered border fence with Egypt and two more died while driving in Rafah town, Palestinian Arab security officials said.