An estimated 500,000 people have fled Iraq’s second-largest city following its capture by al-Qaeda militants. The Islamic State of Iraq and the Levant — ISIL — seized Mosul on Tuesday with a sweeping attack on the city’s airport, TV stations, government buildings and prisons, setting over 2,000 inmates free. The capture of Mosul expands ISIL’s western stronghold after taking Fallujah and parts of Ramadi earlier this year. Iraqi Prime Minister Nouri al-Maliki has declared a national state of emergency. The Iraqi government has struggled to contain spiraling internal violence since the departure of U.S. troops in 2011. The conflict between Sunni militants the Shiite-led government is an outgrowth of the 2003 invasion, which helped spark a civil war.