Millions of Egyptians voted freely Saturday for the first time in more than half a century, waiting for hours to cast their ballots on a package of constitutional changes eliminating restrictions on political rights and civil liberties.
Young people traded mobile-phone pictures of ink-stained fingers that showed they voted. Others called relatives to boast of casting their first vote.
However, the first test of Egypt's transition to democracy offered hints of widening sectarian division.
Many were drawn to the polls in a massive, last-minute effort by the Muslim Brotherhood, the Islamist group that is Egypt's largest and most coherent political organization after the widely despised National Democratic Party of former President Hosni Mubarak, who was ousted last month in a national popular uprising.
The constitutional amendments would open elections to independent candidates, allowing parliamentary and presidential elections to replace the caretaker military government by early 2012.
Critics say that is too soon for the dozens of political groups born out of the 18-day anti-Mubarak uprising to organize themselves and be able to effectively compete in elections.
Instead, they say, the timeframe would benefit Mubarak's National Democratic Party and the Muslim Brotherhood -- the two most powerful political groups in Egypt.
The NDP is blamed for the rampant corruption and the fraud that marred every election in Egypt during Mubarak's 29-year rule. The Brotherhood, which has strongly campaigned for the adoption of the changes, advocates the installment of an Islamic government in Egypt.
Among those most fearful of the Brotherhood's rising power are Egypt's 8 million Coptic Christians, whose leaders rallied the faithful to vote "no."
Brotherhood supporters held demonstrations to campaign for a "yes" vote.
Reform campaigner Mohamed ElBaradei and a group of his supporters were pelted with rocks, bottles and cans outside a Cairo polling center in an attack he blamed on followers of the old regime.
The attack on ElBaradei, the former head of the U.N. nuclear watchdog agency, forced him to flee in an SUV without casting his ballot.
The day was otherwise peaceful. The Egyptian Association for Community Participation Enhancement said it expected the turnout to reach 50 percent, more than three times the average in the rigged elections held under Mubarak.
Preliminary results will be announced today.
Meanwhile, in Yemen, a government crackdown that killed dozens of protesters on Friday failed to stop massive demonstrations Saturday against the Persian Gulf country's U.S.-backed president, as thousands clashed with security forces.
In the capital of Sana, the government had to bring out tank units and other military forces to protect key buildings as crowds swelled. Protesters also stood their ground in the southern city of Mualla, surging out of their destroyed encampment and encircling a police station. In the southern city of Dar Saad, witnesses said protesters chased security authorities out and were now in control.
More than a month of daily protests calling for political freedoms and an end to corruption have presented President Ali Abdullah Saleh with the most dire challenge in 32 years.
In Paris, U.S. Secretary of State Hillary Rodham Clinton warned Iran to stop meddling in Bahrain and other Arab states in the Persian Gulf but called on the kingdom's leaders not to use force against protesters.
Clinton said the United States "has an abiding commitment to Gulf security" and that "a top priority is working together with our partners on our shared concerns about Iranian behavior in the region."