Shi'ite rebel leaders in northern Yemen say government forces have fired on an anti-government protest, killing four people and injuring at least seven others.
A rebel spokesman announced the deaths Friday in northern Yemen, in or near the town of Harf Sofyan.
Tens of thousands of protesters have also gathered in the capital, Sanaa, to call for the ouster of President Ali Abdullah Saleh.
And in the southern city of Aden, tens of thousands of mourners attended the funerals of three demonstrators killed last week.
Thursday, opposition groups presented president Saleh with a plan for a transition of power, in an effort to end the political crisis that erupted in the country last month.
Saleh has not responded to the proposal. He has said he will not seek re-election when his current term expires in 2013.
Anti-government protests have taken place across Yemen since last month, with at least 24 people killed by government loyalists since the demonstrations began.
Some information for this report was provided by AFP and Reuters.
Video footage of Yemen protests