At least 15 people have been killed as clashes between Iraqi security forces and supporters of a powerful Shia cleric continued in Baghdad overnight.
Officials say dozens more were injured after protesters loyal to Muqtada al-Sadr stormed the presidential palace.
The violence was sparked after Mr Sadr announced his retirement from politics.
Iraq's caretaker prime minister has called for calm and the military has declared a nationwide curfew after unrest in several other cities.
Street fighting erupted overnight, as fighters exchanged gunfire and tracer rounds illuminated the night sky in some of the worst violence to hit the Iraqi capital in recent years.
Much of the fighting has been concentrated around the city's Green Zone, an area that houses government buildings and foreign embassies.
Security officials said some of the violence was between the Peace Brigades, a militia loyal to Mr Sadr, and members of the Iraqi military.
Iran has closed its borders with Iraq amidst the fighting, and Kuwait has urged its citizens to leave the country immediately.
Mustafa al-Kadhimi, the interim prime minister and an ally of Mr Sadr, has suspended cabinet meetings and has pleaded with the influential cleric to intervene and stop the violence
Mr Sadr, 48, has been a dominant figure in Iraqi public and political life for the past two decades. His Mehdi Army emerged as one of the most powerful militias which fought US and