1635 GMT: Al Jazeera AND Al Arabiya both report heavy gunfire in Tunis, with many injured. Al Jazeera reports tear gas in front of the Ministry of Interior.
The curfew is now from 5 p.m. to 7 a.m.
1625 GMT: A summary of the turn this afternoon, as peaceful protest gave way to conflict....
Wire services report that 8000 people were demonstrating outside the Ministry of Interior, chanting, "Ben Ali, leave!" and "Ben Ali, assassin!", when gunshots rang out and police fired tear gas to disperse them. Crowds of youths who retreated a short distance from the building started throwing stones at the police, who responded by firing more tear gas grenades.
This version differs from an earlier report that the tear gas was fired when protesters got onto the roof of the Ministry (see 1400 GMT).
1545 GMT: I'm back from Manchester --- thanks to Ali Yenidunya for keeping the LiveBlog ticking over --- to find stunning developments. News came through 45 minutes that President Ben Ali had announced he was dismissing the Government and calling elections within six months.
Now I learn that a state of emergency has been declared. State television says security forces can use force to halt a suspect after giving a warning. No more than three people can assemble in a public space.
The only path forward I can see which doesn't involve significant bloodshed and chaos is a "soft coup," with a caretaker government and promise of rapid move to elections. I hope that somebody -- the Obama administration, King Abdullah of Saudi Arabia, President Sarkozy -- is ready to make that quiet phone call and tell Ben Ali that his service to his nation has come to an end. This could end well… or it could end bloody.