BEIRUT, Lebanon — Several thousand angry protesters smashed the windows and ransacked the offices of the headquarters of the United Nations in Beirut yesterday, venting their rage at Israel, the United Nations, and America after the Qana attack.

What began as a mild protest by about 100 protesters turned violent as hundreds more people, many waving Hezbollah flags and chanting “Death to America! Death to Israel!” flooded into the city’s Riad Al Sohl Square. “Down with the United Nations who allow this Israeli murder,” one man shouted.

“This is Israeli murder. Plain and simple. They are killing us — the Lebanese people, taking our lives and homes. We will all fight them,” Kamal Wazzine, whose family is from Qana, said. He was wearing a yellow Hezbollah bandana.

The marauding few downed their sticks and bats only when two Hezbollah members of parliament, using loudspeakers, urged the demonstrators to stop. “I know you are angry, but I appeal to you to go home.This is not in our interest politically,” the parliament speaker, Nabih Berri, said on local television.

Shortly afterward, dozens of Lebanese soldiers arrived at the scene and cordoned off the building.

A U.N. statement said there were more than 80 Lebanese and foreign staff members in the building. The demonstrators smashed offices and equipment on two floors. A fire was contained shortly after it started, it said. No U.N. staff members were injured.

There was not one shred of blame or anger against Hezbollah, which through this one Israeli attack has gained enormous popular support.

Speaking with a microphone, the popular Lebanese singer Julia Butros, a Christian from the South famous for her anti-Israeli patriotic songs during the 1982 Israeli invasion of Lebanon, caught the public mood, blaming Arab leaders and Israel.

“Thank you, Arab rulers, for your silence on these Israeli attacks, which makes you accomplices in the murder of Lebanese people,” she said as the crowd jeered. “Thank you, Israeli children, for sending your presents to the children of Qana, who United Nations fortunately couldn’t open them because they were asleep.”

In the crowd, which included many women and children, Salma Salam, who described herself as a moderate Shiite, said: “The Israelis have done it again, committed a blatant murderous attack on Lebanese children at Qana again. Ten years on.”

She referred to the Israeli bombing of a U.N. base in Qana in 1996 that killed more than 100 people sheltering there.

There remained lots of support for Sheik Hassan Nasrallah, Hezbollah’s leader who has been hiding out in an impregnable bunker in Lebanon, as demonstrators repeatedly chanted his name.

“I will support Nasrallah now. He is the only one who can fight the Americans and Israelis,” Ms. Salam said.

Hezbollah vowed to punish Israel. “This horrible massacre, like the others, will not remain unpunished,” the group said in a statement.