Half a million people were estimated Wednesday to have fled Iraq's second city of Mosul, as Islamist militants tightened their grip after overrunning it and a swathe of other territory.
In a spectacular blow to the Shiite-led government, the jihadists spearheaded by the Islamic State of Iraq and the Levant (ISIL) on Tuesday seized Mosul, its surrounding region of Nineveh and areas of Kirkuk and Salaheddin province.
On Wednesday they tried to take Baiji in Salaheddin province but withdrew when the army and police reinforcements arrived, officials said.
Their surprise advance poses significant challenges to Baghdad, with analysts saying they would be bolstered by cash from Mosul's banks, hardware from military bases and hundreds of men they freed from prison.
It also sparked a massive exodus, with families seen piling into cars that crammed security checkpoints outside the northern city, which is normally home to a population of two million people.
Prime Minister Nuri al-Maliki responded by asking parliament to declare a state of emergency and announcing citizens would be armed to fight them, while the United States warned ISIL threatened the entire region.
On Wednesday, gunmen in military uniforms and all-black clothing guarded government buildings and banks in Mosul, said witnesses reached by telephone from Bashiqa, a town to the east.
They called over loudspeakers for government employees to go back to work.
"I did not open the door of the shop since last Thursday because of the security conditions," said Abu Ahmed, a 30-year-old shop-owner.
The International Organisation for Migration said around half a million Iraqis had fled their homes in Mosul following the city's fall, fearing increased violence.
The Geneva-based organisation said its sources on the ground estimated the violence leading up to the jihadists' total takeover "displaced over 500,000 people in and around the city".
- 'Mosques converted to clinics' -
The violence in Mosul "has resulted in a high number of casualties among civilians," the IOM said, adding that fighting restricted access to the main health campus grouping four hospitals.
"Some mosques have been converted to clinics to treat casualties," it said.
Witnesses reported that dozens of families continued to flee the city, but Abu Ahmed said: "I will remain in Mosul. This is my city in any case, and the city is calm now."
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Bassam Mohammed, a 25-year-old university student, also said he would stay in Mosul.
"But I am afraid about freedoms, and I am especially afraid that they will impose new laws on us," Mohammed said.
ISIL said it was behind operations in Nineveh in a series of messages on Twitter, while officials have also blamed the jihadist Sunni group for the unrest.
But it is possible other militant groups were also involved.
Known for its ruthless tactics and suicide bombers, ISIL is arguably the most capable force fighting President Bashar al-Assad inside Syria as well as the most powerful militant group in Iraq.
- 'Entire region threatened' -
The takeover of Mosul prompted the United States to voice deep concern about the "extremely serious" situation and warn that ISIL poses "a threat to the entire region".
UN chief Ban Ki-moon's spokesman said he was "gravely concerned by the serious deteriorating of the security situation in Mosul".
ISIL is led by the shadowy Abu Bakr al-Baghdadi and backed by thousands of Islamist fighters in Syria and Iraq, many of them Westerners, and it appears to be surpassing Al-Qaeda as the world's most dangerous jihadist group.
The New York-based Eurasia Group consultancy said ISIL's capture of Mosul would have limited impact on Iraq's oil exports.
"ISIS will use cash reserves from Mosul's banks, military equipment from seized military and police bases, and the release of 2,500 fighters from local jails to bolster its military and financial capacity," said Ayham Kamel, its Middle East and north Africa director.
"We do not anticipate a sharp deterioration in the security environment in these more stable provinces that would materially impact Iraq's oil export volumes," he said.
Iraq, which boasts among the highest reserves of oil and gas in the world, produces about 3.5 million barrels of oil per day, with exports in February reaching 2.8 million bpd, the highest such figure in at least a quarter-century.
A senior government official said "the oil sector is not affected and will not be affected by what is happening, because most of the facilities are in central and south Iraq," though he warned that further militant advances could change this.
Bloodshed is running at its highest levels in Iraq since 2006-2007, when tens of thousands were killed in clashes between the country's Shiite majority and Sunni Arab minority.