ABIDJAN, Ivory Coast  At least four demonstrators, including a 19-year-old woman, were shot dead by riot police officers on Tuesday as they protested the shooting deaths of women who marched last week, witnesses said.

Volleys of bullets fired by the security forces of the nation’s strongman, Laurent Gbagbo, continued to sound around the clinic where the dead were taken Tuesday afternoon, as relatives and others pressed for cover inside the tiny building in the Treichville district. Three of the bodies lay on the floor under bloodied sheets, while a wounded man gasped in pain in the hall.

Mr. Gbagbo’s refusal to give up power after losing a presidential election last November is yielding a mounting toll of death, lawlessness and economic collapse here in this sprawling commercial capital of nearly four million people.

Gunfire sounds across the city every day, and youths with machetes and pistols staff impromptu checkpoints. Nearly 400 have died in all, according to the United Nations, including at least seven women last week who were cut down while protesting in the rebellious Abobo neighborhood by large-caliber machine-gun fire from Mr. Gbagbo’s security forces.