(Newser) – ISIS militants have seized a key Iraqi city while coalition airstrikes continued raining down around them, officials say. The militants had already taken most of Ramadi, the capital of Anbar province, placing their flag at the city's government headquarters on Friday—but Iraqi special forces still held out in the Malaab neighbourhood, Al Jazeera reports. Now those forces have fled despite pleas from Iraq's prime minister to hold their positions, the AP reports. Amid the chaotic invasion, government officials apparently requested help from Shia factions, but others warned that Sunni tribal allies might retaliate. "There are many influential tribes in Anbar who have warned against this decision for some time now," says an Al Jazeera reporter.

Ramadi is the first important city seized by ISIS since it took Mosul last June, and Iraqi forces supported by US-led air strikes started retaliating against the militants, the Independent reports. The US chair of the joint chiefs of staff recently described Ramadi as "not symbolic in any way." But in an Al Jazeera blog post, security correspondent Imran Khan says the city of 500,000 is considered a key area of Sunni dissent against the Iraqi government. "Ramadi is the heart of Anbar," an Iraqi diplomatic source tells Khan. "What happens if you destroy the heart? The whole body dies." (Read more Ramadi stories.)

