BAGHDAD - Tens of thousands of Iraqis surged into the streets Friday in at least a dozen demonstrations across the country, storming provincial buildings, forcing local officials to resign, freeing prisoners and otherwise demanding more from a government they only recently had a chance to elect.

At least 23 protesters were killed as Iraqis braved security forces to vent shared frustrations at the nearest government official. Sunnis, Shiites, Kurds and Christians, they shouted for simple dignities made more urgent by war - adequate electricity, clean water, a decent hospital, a fair shot at a job.

"I have demands!" Salma Mikahil, 48, cried out in Baghdad's Tahrir Square, as military helicopters and snipers looked down on thousands of people bearing handmade signs and olive branches signifying peace. "I want to see if Maliki can accept that I live on this," Mikahil said, waving a 1,000-dinar note, worth less than a dollar, toward Prime Minister Nouri al-Maliki's offices. "I want to see if his conscience accepts it."

The protests - billed as Iraq's "Day of Rage" - represented a new sort of conflict for a population that has been menaced by sectarian militias and suicide bombers. Now, many wondered whether they would have to add to the list of enemies their own government, whose security forces beat and shot at protesters and journalists Friday and left hundreds injured.

Six people were killed in Fallujah and six others in Mosul, with the other deaths reported in five separate incidents around the country, according to officials and witnesses. The reports attributed most casualties to security forces who opened fire.

The demonstrators who sparked the crackdown were calling for reform, not revolution, although there were mini-examples of the latter - hyper-local versions of the recent revolts in Egypt, Tunisia and Libya. Crowds forced the resignation of the governor of the southern province of Basra and the entire city council of Fallujah and chased away the governor of Mosul, the brother of the speaker of parliament, who was also there and fled, too.

The protests began peacefully but grew more aggressive. Angry crowds seized a local police station in Kirkuk, set fire to a provincial office in Mosul and rattled fences around the local governate offices in Tikrit, prompting security forces to open fire with live bullets. At least three people were reported killed in the Tikrit area and three others in Kirkuk.

By sundown in Baghdad, security forces were spraying water cannons and exploding sound bombs to disperse protesters, chasing several through streets and alleyways and killing at least three, according to a witness.

Two people were also reported killed in Kurdistan, in the north.

The day's events posed a unique challenge for the Obama administration, which has struggled to calibrate its responses to the protests rolling across the Middle East and North Africa but has a particular stake in the stability of the fledgling democracy it helped usher in.

Analysts said Friday's developments were at best awkward for the United States.

"Obama wants to convey that 'Yes, Iraq has a number of problems that need to be addressed, but the country is on the right track,'" said Joost Hiltermaan, deputy director for the International Crisis Group's Middle East program. "You can't possibly say, 'Iraq is in a crisis, and by the way, we're leaving.' "

The United States is set to complete the withdrawal of all its troops from Iraq by the end of the year.

The U.S. Embassy in Baghdad played down Friday's violence, as well as the draconian measures Maliki took to stifle turnout.

Iraq's security forces "generally have not used force against peaceful protesters," said Aaron Snipe, an embassy spokesman. "We support the Iraqi people's right to freely express their political views, to peacefully protest and seek redress form their government. This has been our consistent message in Iraq and throughout the region."

The turnout Friday appeared to surprise many of the demonstrators, coming as it did after a curfew on cars and even bicycles forced people to walk, often miles, to participate. There were also pleas - some described them as threatening - from Maliki and Shiite clerics, including the populist Moqtada al-Sadr, to stay home.

Sadr, whose Mahdi Army is blamed for some of the worst sectarian violence of the war, is now part of Maliki's governing coalition and attempting to position himself as both insider and outsider. Sadr's power lies in his rare ability to call hundreds of thousands into the streets, and analysts said he is perhaps concerned about losing his impoverished urban followers to the new and still only vaguely unified protest movement .

By mid-morning in Baghdad, people were walking toward Tahrir Square along empty streets fortified with soldiers in Humvees, snipers on rooftops and mosque domes and checkpoints with X-ray equipment that might reveal a suicide vest.

Young and old, some missing legs and arms, some chanting old slogans of the Mahdi Army, the protesters passed crumbling high-rise apartment buildings webbed with electrical wires hooked to generators. At times, the air smelled like sewage.

"Bring electricity!" they shouted, and "No to corruption!"

By afternoon, several thousand people were milling around the square, which is next to a bridge leading to the heavily guarded international zone housing the government's offices. Overnight, security forces had hauled in huge blast walls to block the bridge from protesters, who nonetheless managed to hoist a rope around one of them and pull it down.

"As you can see, they are hiding behind this wall!" shouted Sbeeh Noman, a white-haired engineer who said he walked 12 miles to reach the square and was now heading for the bridge. "The government is afraid of the nation. They have found out that the people have the real power."

Special correspondents Ali Qeis and Aziz Alwan contributed to this report.