At least two people were shot and several other people wounded during unrest that erupted during demonstrations in Caracas against Venezuela's President Hugo Chavez.
Shots were fired from within crowds supporting Chavez at opponents of the president who have been on strike for the past month.
Police opened fire on gunmen in the crowds after an officer was shot in the knee.
The disturbances came as hundreds of thousands of people took part in an anti-Chavez march to the main Fuerte Tiuna military complex in Caracas.
A policeman at the scene said at least six Chavez supporters were firing guns at the opposing crowd and an 18-year-old paramedic suffered a bullet wound to the abdomen.
A police officer and a national guardsman were injured as rocks were thrown by both sides.
Several other people were treated for tear gas exposure. Troops who had earlier fired volleys of tear gas in an attempt to keep the two sides apart sent more tear gas into the crowds in a bid to separate them.
