A suicide bomber driving a car killed at least 19 people and wounded 48 others on Saturday in an attack claimed by Islamic State on an outdoor food market in a southeastern suburb of Baghdad, while supporters of Shiite cleric stormed parliament.
A second explosion near a Shiite militia checkpoint in the capital's Dora district killed two and wounded three others, police sources said. There was no immediate claim of responsibility for that blast.
Amaq news agency, which supports Islamic State, said a fighter in the Nahrawan district had driven a truck loaded with three tons of explosives into a gathering of Shiite pilgrims. But other reports say the bomber actually exploded in a market and did not directly attack Saturday's Shiite pilgrimage, which passes nearby the market. Thousands of Shiite pilgrims are making the trek to Baghdad's Imam Kadhim shrine to commemorate the 8th century death of one of Shiite Islam's senior figures.
Warning: Video shows the aftermath of the bombing in Baghdad, including wounded and dead people.
Later on Saturday in Baghdad, hundreds of supporters of Muqtada al-Sadr stormed into Baghdad's Green Zone and entered parliament after Sadr denounced politicians' failure to reform a political quota system blamed for rampant corruption.
The protesters, who had gathered outside the heavily fortified district housing government buildings and many foreign embassies, crossed a bridge over the Tigris River chanting: "The cowards ran away!" in apparent reference to departing lawmakers.
Inside parliament hundreds of protesters danced, waved Iraqi flags and chanted pro-Sadr slogans. Some appeared to be breaking furniture.
Rudaw TV showed them chanting and taking pictures of themselves inside the main chamber where moments earlier lawmakers had met.
There were no reports of clashes with security forces. But an army special forces unit was dispatched with armored vehicles to protect sensitive sites, two security officials said. No curfew has been imposed, they said.
All entrances of Baghdad were shut "as a precautionary measure to maintain the capital's security," another security official said.
A United Nations spokesman and Western diplomats based inside the Green Zone said their compounds were locked down. A US embassy spokesman denied reports of evacuation.
Sharqiya TV showed Prime Minister Haider al-Abadi walking inside the Green Zone with dozens of armed guards following the breach, discrediting reports he had fled. Protesters later entered the nearby cabinet headquarters.
Such a breach is unprecedented, though only a few years ago mortars frequently rained down on the 10-square-kilometre Green Zone, which once housed the headquarters of the US occupation and before that a palace belonging to Saddam Hussein.
Checkpoints and concrete barriers have blocked bridges and highways leading to the neighborhood for years, symbolizing the isolation of Iraq's leadership from its people.
Video showed protesters attacking a white, armored SUV with sticks and other objects on Saturday. In separate footage, they beat a man wearing a gray suit.
Sources in Sadr's office said several Kurdish deputies who had been holed up inside parliament were evacuated by a Sadrist MP in his motorcade.
A Kurdish peshmerga guard at a checkpoint said the protesters surged in after security forces pulled back from an external checkpoint in an unsuccessful effort to secure parliament. They had not been searched before entering the Green Zone, he said.
About ten members of the armed group loyal to Sadr were checking protesters cursorily as government security forces who usually conduct careful searches with bomb-sniffing dogs stood by the side.
Thousands more protesters remained at the gates chanting "Peaceful!". Some stood atop concrete blast walls that form the district's outer barrier.
A Sadr spokesman said the cleric called on supporters to evacuate parliament and set up tents outside, according to Reuters.
"Negotiations are ongoing between security and government officials and protesters' representatives to make sure their demands are met," said Sheikh Muhanad al-Gharrawi.
President Fuad Massoum called on protesters to leave parliament but added: "Burying the regime of party and sectarian quotas cannot be delayed."
Parliament failed to reach quorum earlier on Saturday to complete voting on a cabinet reshuffle proposed by Abadi after a handful of ministers were approved on Tuesday despite disruptions by dissenting lawmakers.
Political parties have resisted Abadi's efforts to replace some ministers — chosen to balance Iraq's divisions along party, ethnic and sectarian lines — with technocrats in order to combat corruption.
Supporters of Sadr, whose fighters once ran swathes of Baghdad and helped defend the capital from Islamic State in 2014, have been demonstrating in Baghdad for weeks, responding to their leader's call to put pressure on Abadi to follow through on months-old reform promises.
Moments before the Green Zone breach, Sadr seemed to offer an ultimatum: "Either corrupt (officials) and quotas remain or the entire government will be brought down and no one will be exempt from that."
In a televised speech from the holy city of Najaf announcing a two-month withdrawal from public life, Sadr said he was "waiting for the great popular uprising and the major revolution to stop the march of the corrupt."
Abadi has warned that delays to overhauling the cabinet could hamper the war against Islamic State, which controls vast swathes of northern and western Iraq.
"Burying the regime of party and sectarian quotas cannot be delayed."
Security has gradually improved in Baghdad, which was the target of daily bombings a decade ago, but attacks against both the security forces and civilians are still frequent.
The rise of Islamic State, which is fighting government forces for control of swathes of northern and western Iraq, has exacerbated the country's sectarian conflict, mostly between Shiites and Sunnis, which emerged after the 2003 US-led invasion.
Also on Saturday Islamic State militants launched an offensive near the northern town of Baiji, which Iraqi forces and Shiite militia fighters recaptured months ago along with a large oil refinery devastated by the conflict.
In the first set of attacks on Friday evening near Siniya west of Baiji, Islamic State seized four security checkpoints, according to sources in Salahuddin operations command. The militants used car bombs, killing 11 members of the security forces and wounding 12 others.
From the eastern side of Baiji, the militants attacked security forces near Makhoul, killing three police officers and wounding two others in fighting that continued on Saturday, the sources said.
Watch VICE News' video, What It's Really Like to Fight for the Islamic State: