CAIRO (CNN) -- The Cairo courtroom erupted in chaos Saturday after an Egyptian judge convicted former President Hosni Mubarak, but acquitted six of his aides, for the killing of protesters during last year's pro-democracy uprising.

The judge handed Mubarak, 84, a life sentence.

It appeared the entire gallery of men dressed in suits began shouting and stood on their chairs chanting that the decision wasn't harsh enough. Fists flew and at least one man suffered a bleeding gash to his chin.

"We want honesty!" they shouted. "Revolution til victory!"

Other Mubarak opponents headed to Tahrir Square, the center of last year's protests, shouting, "Illegitimate! Illegitimate!" They also chanted for Mubarak's execution.

Vowing not to leave, the crowd later forced the square to be shut down.

The echoing cheers outside the police academy where the trial was held turned to angry shouts as people heard that all of Mubarak's senior advisers and his two sons were acquitted.

The mostly anti-Mubarak crowd threw rocks at police, smashed cars, and cursed the ruling military council.

Mubarak was immediately transferred to a prison in southern Cairo to serve his life sentence, a prosecutor said, a final fall from grace for a man who ruled the nation with an iron fist for nearly three decades.

"Mubarak arrived to Tura prison by helicopter, and will be admitted to a hospital in prison," said Adel Saeed, a spokesman for the prosecutor. A spokesman for the Interior Ministry said Mubarak refused to leave the helicopter on arrival at the prison.

About 840 people died and more than 6,000 others were injured in last year's 18-day uprising, according to Amnesty International.

Arab leaders: Where are they now?

The sentence delivered by Judge Ahmed Refaat was the final chapter of Mubarak's iron rule of Egypt that ended in February 2011.

Handing down the verdict before a packed courtroom, the judge praised the revolution, saying it offered people relief after living "in 30 years of dark without any hope."

He found Mubarak guilty of the killings, but cleared him of corruption and misappropriation of funds.

The judge also convicted former Interior Minister Habib El Adly of ordering security forces to kill protesters and sentenced him to life in prison.

The courtroom melee erupted after the judge cleared six of Mubarak's aides, primarily security officials, in connection with the killings. Authorities removed Mubarak and the judge from the courtroom amid the outburst.

The judge also cleared Mubarak's sons, Gamal and Alaa, of corruption and using their father's political power for profit.

"The verdicts are insults to the Egyptian people and the judicial system. It's a festival of innocent verdicts to El Adly's aides who killed and tortured free citizens for years," said Rami Shath, a member of the Egyptian Revolution Alliance.

Human Rights Watch said the verdict sends a message to Egypt's future leaders that they are not above the law, though it said the acquittals give "a green light to future police abuse."

Amnesty International said the verdict is "a significant step towards combating long-standing impunity in Egypt," but it, too, said the ruling leaves many waiting for full justice.

David Scheffer, an American lawyer and diplomat who served as the first U.S. ambassador-at-large for war crimes issues, said it the trial was significant for the Arab world even if it could have been run better.

"While I want to emphasize the problems with the trial itself, it's also important to recognize that the Egyptian judicial system has held a leader accountable for very serious crimes that occurred during the uprising in Egypt," Scheffer told CNN.

"In the very heart of the Arab world, where this has not occurred before in a civilian court, a leader has actually been brought to to justice, a leader who has been present in the courtroom has brought to some level of justice by a domestic court for gross human rights abuses."

The trial has been a spectacle few Egyptians thought they would see. Images broadcast worldwide showed the 84-year-old former leader wheeled into the court on a hospital gurney and locked in a defendant's cage.

The verdict follows Friday's expiration of a notorious emergency law that was in effect since shortly after Mubarak came to power in October 1981 and gave police sweeping powers. It comes ahead of a polarizing mid-June runoff in the presidential election that pits the Muslim Brotherhood's Mohamed Morsi against the more secularist Ahmed Shafiq, a former official in Mubarak's regime.

Analysts in Egypt say the verdict may not help Shafiq and may strengthen Morsi's chances, given his position as an opposition figure.

The Muslim Brotherhood said it is not happy with Saturday's verdict and may call for a retrial. Shafiq's side did not immediately comment on the outcome.

CNN's Saad Abedine and Mohamed Fadel Fahmy contributed to this report.