Hundreds of protesters loyal to a powerful cleric on Saturday stormed the fortified “Green Zone,” where government buildings and foreign embassies are located, storming parliament and raising fears the political system nurtured by the U.S. could unravel.

The protesters, loyal to popular Shiite cleric Muqtada al-Sadr, echoed their leader's call for government reformation. Sadr, who once controlled various territories inside the Iraqi capital, has called for Baghdad’s government to root out corruption he claims is rife throughout the post-Saddam Hussein Iraqi political system.

The protests disbanded on Sunday and protesters began filing out of the Green Zone in an orderly manner. But Saturday the tenor was quite different.

"We want to kick out irresponsible politicians for their positions and create a massive reform for all Iraqis and Iraq," one protester, Iraqi student Anmar Fadal, 22, told FoxNews.com. "I wish for peace and safety and the end of corruption."

Fadal and others said new faces must “build the country.” Aram Bodo, a Christian medical student from a village just outside of Mosul, was among scores of protesters who occupied Parliament House - walking some 10 miles with other protesters and sweeping through the security checkpoints that had previously kept the Green Zone insulated.

Supporters of al-Sadr have been holding demonstrations and sit-ins for months to demand an overhaul of Iraq's corrupt and ineffective political system, but Saturday was the first time they broke into the Green Zone. While mostly nonviolent and with a celebratory air ta even included guards offering water to protesters, the mob scene underscored al-Sadr’s muscle, and the pressure his followers can exert.

"I want rights for all Iraqi people. I want an end to the corruption and a return of all the stolen public money," Bodo said. "I want a creation of an autonomous rule for the Christians and other minorities in our areas, without the control of any other power," Bodo continued.

Demonstrators took scores of selfies and other cell phone pictures and video, some showing them playing soccer inside the Parliament grounds, swimming in the canals that were once reserved for Hussein and his top ministers, and even cleaning the floors of government buildings as politicians fled in armored vehicles.

"The security forces just asked that we don't damage public property," one demonstrator, Zulfikar Haidari said. "Everyone should know that these demonstrations are peaceful and involve everyone from all religions and groups. Everyone wants to improve the situation. I am proud of everyone, we have come out against political traitors and criminals."

Haidari also noted that there was "great cooperation" between protesters and the security forces.

According to Saifaden A Satar, a captain in Baghdad’s Presidential Guard, guards were overwhelmed by the sheer number of protesters, and elected to let them through the gates.

"There hasn't been gunfire at all. At the beginning of the intrusion there were a few tear gas grenades thrown from cops," he told FoxNews.com. "But security forces eased up situation and let the protesters as they were not armed."

The political chaos comes as the country is not only tackling sectarian tensions between communities and a steep drop in oil prices, but is still trying to run Islamic terrorist group ISIS out of areas it has tightly controlled for almost two years.

Many of expressed concern that the political crisis will further delay and hinder efforts to squash the ISIS presence, although multiple protesters insisted to FoxNews.com that they were also pushing for the government to liberate these areas faster and sooner - insisting delays were a result of internal corruption and squabbling.

Iraqi security forces initially responded by tightening security across the capital, sealing off checkpoints leading to the Green Zone and halting traffic on main roads heading into the city, according to the Baghdad Operations Command.

But Iraq's elite counterterrorism forces, who have in the past been called on to reinforce security in the capital, said they are standing down for now.

"We still view this as a demonstration," said Sabah al-Numan, spokesman for the counterterrorism forces. "We aren't taking any part in this as it's not something regarding terrorism."

The protests were not completely nonviolent, according to witnesses who said Shia Member of Parliament Ammar Tauma was physically attacked and his vehicle set upon Sunday morning, the first day of the working week in Iraq.

Video posted online showed a group of young men slapping an Iraqi lawmaker – possibly Tauma - as he attempted to flee the crowd, and protesters mobbing another lawmaker's motorcade inside the Green Zone. The footage appeared authentic and corresponded with AP reporting.

Prime Minister Haider al-Abadi has since stated that the security situation is under control, but the United Nations Assistance Mission for Iraq has referred to the developing unrest as "gravely concerning" and called for "calm, restraint and respect for Iraq's constitutional institutions at this crucial juncture."

Al-Sadr and his supporters want to reform the political system put in place following the U.S.-led invasion in 2003, in which entrenched political blocs representing the country's Shiites, Sunnis and Kurds rely on patronage, resulting in widespread corruption and poor public services.

Iraqi security forces initially responded by tightening security across the capital, sealing off checkpoints leading to the Green Zone and halting traffic on main roads heading into the city, according to the Baghdad Operations Command.

But his supporters make up the second largest parliamentary bloc, with 34 seats in the 328-member assembly, and controlled three ministries before the latest upheaval.

FoxNews.com’s Hollie McKay and Steven Nabil and The Associated Press contributed to this report.