Yemen unrest: 'Dozens killed' as gunmen target rally
Unidentified gunmen firing on an anti-government rally in the Yemeni capital Sanaa have killed at least 39 people and injured 200, doctors told the BBC.
The gunmen fired from rooftops overlooking the central square in what the opposition called a massacre.
President Ali Abdullah Saleh later declared a national state of emergency.
Richard Slee reports.