Israeli Foreign Ministry spokesman Arye Mekel said Israel has no forces on the Gaza-Egypt border and, "therefore it is the responsibility of Egypt to ensure that the border operates properly, according to the signed agreements."
"We expect the Egyptians to solve the problem," Mekel said. "Obviously we are worried about the situation. It could potentially allow anybody to enter."
Israeli defense officials said they were concerned Hamas could use the opening of the border to bring weapons and ammunition into Gaza. They spoke on condition of anonymity because the defense ministry had issued no official statement.
The gunmen began breaching the wall dividing Rafah before dawn, according to witnesses and Hamas officials. A total of 17 explosions destroyed the Rafah wall Wednesday, Hamas security officials said. The officials, who spoke on condition of anonymity due to the sensitivity of the matter, said they were allowing Palestinians to move freely through two gaps.
The identity of the gunmen who breached the border was not immediately clear. But Hamas expressed support for the move, saying that, "Blowing up the border wall with Egypt is a reflection of the ... catastrophic situation which the Palestinian people in Gaza are living through due to the blockade."
Thousands of Gazans began crossing into Egypt and returning with milk, cigarettes and plastic bottles of fuel.
Two-thirds of the Rafah wall had been demolished by 10 a.m. and the crowd of Palestinians crossing into Egypt swelled into the tens of thousands.
Israel expressed concern that militants and weapons might be entering Gaza amid the chaos, and said responsibility for restoring order lay with Egypt.
Egypt has largely kept its border with Gaza closed since the Hamas takeover amid concerns of a spillover of Hamas-style militancy into Egypt. But Egypt's government is also under popular pressure at home to help the impoverished Gazans.
Egyptian public opinion is sympathetic to the Palestinians, and most political analysts believe Mubarak's regime would face a serious crisis if its forces opened fire on Palestinians during a border melee.
Israel also is in a difficult situation. It is concerned about the free flow of militants and weapons into Gaza, but cannot be seen as criticizing Egypt too strongly, for fear of alienating an important Arab country.
"Israel has no forces in Gaza or Egypt, and the Egyptians control the border, and therefore it is the responsibility of Egypt to ensure that the border operates properly according to the signed agreements. We expect the Egyptians to solve the problem," said Arye Mekel, a spokesman for Israel's Foreign Ministry.
"Obviously we are worried about the situation. It could potentially allow anybody to enter," Mekel said.
Palestinians have broken through the Egypt border several times since Israel pulled out of Gaza in 2005 and stopped patrolling the border. But none of the previous breaches approached the scale of Wednesday's destruction, which demolished two-thirds of the seven-mile border wall.
Gazans walked unhindered over the toppled metal plates that once made up the border wall, carrying goats, chickens and crates of Coca-Cola. Some brought back televisions and car tires. One man bought a motorcycle. Vendors sold soft drinks and baked goods to the crowds.
Within hours, shops on the Egyptian side of the divided border town of Rafah had run out of most of their wares.
Ibrahim Abu Taha, 45, a Palestinian father of seven, was in the Egyptian section of Rafah with his two brothers and $185 in his pocket.
"We want to buy food, we want to buy rice and sugar, milk and wheat and some cheese," Abu Taha said, adding that he would also buy cheap Egyptian cigarettes.
Abu Taha said he could get such basic foods in Gaza, but at three times the cost.
Moussa Zuroub, a 28-year-old Palestinian, carried his young daughter Aseel on his shoulders, trudging through the muddy streets of Egyptian Rafah.
"I'm coming just to break that ice that all my life, I'd never left Gaza before," Zuroub said.
In Egyptian Rafah, a market stall selling pistols and ammunition clips for Kalashnikov assault rifles had no customers Wednesday. Weapons are generally brought into Gaza through smuggling tunnels under the Gaza-Egypt border.
An off-duty Hamas policeman, who only gave his first name, Abdel Rahman, said there was no need to buy weapons from Egypt.
"You can buy weapons in Gaza, guns and RPGs," he said, adding that they were easier to find than cancer medicine or Coca-Cola.
The destruction of the wall began before dawn Wednesday, when Palestinian gunmen began using land mines, blowing holes in the border wall that runs through Rafah, witnesses said. There were 17 explosions in all, Hamas security officials said. At first, Hamas and Egyptian security officers prevented people from getting through, witnesses said, but by morning thousands of Gazans had massed at the border and overwhelmed police began letting people cross.
Most Egyptian security and police were later pulled out from the immediate vicinity of the border, Egyptian security officials said.
International reaction to the dramatic events was muted.
U.S. Secretary of State Condoleezza Rice said the U.S. wants to see stability in the region, but that "most importantly both the security concerns of Israel and the humanitarian concerns of Gazans be met."
The European Union was to issue a statement later Wednesday.
Wednesday's chaotic scenes came almost a week after Israel imposed a tight closure on Gaza, backed by Egypt, in response to a spike in Gaza rocket attacks on Israeli border towns.
Pictures of children marching mournfully with candles and people lining up at closed bakeries in a blacked-out Gaza City evoked urgent appeals from governments, aid agencies and the U.N. for an end to the closure.
Israel maintained that Hamas was creating an artificial crisis but nonetheless eased the closure slightly on Tuesday, transferring fuel to restart Gaza's only power plant, and also sent in some cooking gas, food and medicine. Israel has pledged to continue limited shipments because of concerns about a possible humanitarian crisis, but Israeli defense officials said Wednesday there would be no new shipments for the time being.
The rocket fire by Gaza militants has sent residents in Israeli border communities scrambling for shelter several times a day. The rockets have traumatized many area residents and killed 12 Israelis in six years. The attacks have persisted despite the closure.
In a clash early Wednesday with Israeli forces near the closed Sufa crossing into Gaza, a Hamas militant was killed, Palestinian officials said. The Israeli military said soldiers exchanged fire with Palestinian militants in the area.
