A few more details on today's rally: It started as a "licensed" (government-approved) march along Budaiya Highway, a major road which runs west of the capital.

But a large group of demonstrators - perhaps as many as 10,000, according to a witness on the ground - broke away and started marching back towards Pearl Roundabout in Manama. They were tear-gassed heavily, and many of them fled.

Said Yousif al-Muhafdah, an activist with the Bahrain Centre for Human Rights, tweeted this photo of protesters running from tear gas: