At least 39 people have been killed in overnight fighting as clashes intensified in the Yemeni capital, Sanaa, doctors and officials say. Medical officials said that the casualties came from both government forces and opposition tribal fighters, who've been fighting street battles in Sanaa. The clashes come as domestic and international pressure continues for President Saleh to step down. Lisa Mullins gets the latest from the BBC's Lina Sinjab in Sanaa.