© AP PhotoA protester holds the Egyptian national flag as a fire burns outside the building housing the Israeli Embassy in Cairo.
A demonstration that brought tens of thousands to this city's central Tahrir Square turned violent on Friday, when thousands of people - led by a heavy contingent of soccer fans - tore down a protective wall around the Israeli Embassy, while others defaced the headquarters of the Egyptian Interior Ministry.

The Egyptian state news agency said 448 people were injured and 17 protesters were arrested in the clashes, mostly around the Israeli embassy. Protesters scaled the walls of the Israeli Embassy to tear down its flag, broke into offices and tossed binders of documents into the streets.

Mustafa el Sayed, 28, said he had been among about 20 protesters who broke into the embassy. He showed a reporter video from a cellphone, of protesters rummaging through papers and ransacking an office, and he said they had briefly beaten up an Israeli employee they found inside, before Egyptian soldiers stopped them. The soldiers removed the protesters from the building, he said, but let them go free.

By 11:30 p.m., about 50 trucks had arrived with Egyptian riot police officers, who filled the surrounding streets with tear gas. Witnesses said that protesters had set a kiosk on fire in front of a security building near the embassy, and that the police had fired rubber bullets to disperse the crowd from both buildings. But at 3 a.m. Saturday, thousands of protesters were still battling thousands of riot police officers. Demonstrators threw rocks and gasoline bombs at the officers, sometimes forcing them to retreat, and the police fired back with tear gas. To celebrate an advance, protesters set off the flares that they typically use to cheer at soccer matches.

Egyptian airport officials said early Saturday that the Israeli ambassador was waiting for a military plane to leave the country, The Associated Press reported.

United States officials said Defense Minister Ehud Barak of Israel had called Defense Secretary Leon Panetta, who in turn asked the Egyptian military to try to restore order at the embassy.

In addition, a fire broke out in the basement of the Interior Ministry, but it appeared to have been started from the inside and not by the protesters surrounding the building. The fire was in a room believed to store criminal records.

The scale of the protests and the damage inflicted represented a departure from the previously peaceful character of the demonstrations staged periodically in Tahrir Square since the revolution in January and February.

Organizers of Friday's demonstrations had said they would call for a list of familiar liberal goals, like retribution against former President Hosni Mubarak and an end to military trials of civilians. But thousands of people marched off from the square to express their anger over disparate recent events, including a recent dispute along the border with Israel and a brawl between soccer fans and the police at a match on Tuesday.

Thousands of hard-core soccer fans - known here as ultras - were for the first time a conspicuous presence in the protests and a dominant force in the violence. They led the attacks on the Interior Ministry and the security building near the Israeli Embassy, and they kept up the fight outside the embassy long after others had gone home. At the Interior Ministry, political activists tried to form human barriers to protect the building, urging protesters to retreat to the square and chanting, "Peacefully, peacefully."

"Those who love Egypt should not destroy it!" they chanted.

The embassy, which has been the site of several previous demonstrations after the Israeli armed forces accidentally killed at least three Egyptian officers while chasing Palestinian militants near the border last month, was an early target on Friday. In response to almost daily protests since the shootings, the Egyptian authorities had built a concrete wall surrounding the embassy, and by early afternoon thousands of protesters, some equipped with hammers, were marching toward the building to try to tear down the wall.

After using the hammers and broken poles to break through sections of the wall, protesters began using ropes attached to cars to pull away sections. By the end of the night, the wall was virtually demolished.

Egyptian military and security police officers largely stood by without interfering with the demolition. Instead, they clustered at the entrance to the embassy to keep protesters out. The security forces had pulled back from Tahrir Square and other areas before the start of the day to avoid clashes with the protesters, although the military had issued a stern warning on its Facebook page against property destruction.

Egyptians outside the embassy seized on the wall as a symbol. "We were attacked inside our own land," said Ahmed Abdel Mohsen, 26, a government employee. "They can't lock us out in a wall in our own country. Nothing will stand in the way of Egyptians again."

The soccer fans turned out in response to a melee with the police after a match on Tuesday. Long known for their obscene chants and reckless brawls, the ultras have become increasingly engaged in politics since the revolution.

The soccer match took place against the backdrop of the trial of Mr. Mubarak and his interior minister, Habib el-Adly, who are accusing of conspiring to kill protesters. The ultras chanted obscene songs denouncing both men and their security forces, and at the end of the match, witnesses said, the security police attacked the ultras, leaving more than 100 people injured and more than 20 fans in jail.

By Friday night, a few hundred protesters had managed to pull down 9 of the 13 letters in the Arabic signs on the wall of the Interior Ministry. And graffiti on the wall went far beyond the soccer brawl to attack the military council running the country in the name of the revolution and its leader, Field Marshal Mohamed Hussein Tantawi.

"Down with the traitorous council!" some of the graffiti read. "Down with the Field Marshal."