From Sanaa, Yemen, The Associated Press reports that:
"Eyewitnesses say Yemeni security forces opened fire on demonstrators taking part in protests throughout Yemen in what appears to be the biggest turnout in a month of unrest to demand regime change."
The AP adds that:
"Many demonstrators say their turnout of hundreds of thousands on Friday is to tell their leader of 32 years that they reject his latest compromise offer and want him to go. [President Ali Abdullah] Saleh proposed creating a new constitution guaranteeing the independence of parliament and the judiciary on Thursday night."
Some videos purporting to show the scale of today's demonstrations are starting to show up on YouTube.
Update at 10:55 a.m. ET. Reuters reports that:
"Fighting broke out between small groups of government supporters and protesters on Friday as record crowds of tens of thousands called for President Ali Abdullah Saleh to quit, dismissing his offer of reforms. Yemenis flooded streets and alleys around Sanaa University in the biggest protest to hit the capital since demonstrations began in January. About 30 people have been killed since then."