AU-PRINCE, Haiti, April 27, SPA -- At least five people were killed on Wednesday in an exchange of fire between police and demonstrators in Haiti, which is preparing for elections in the autumn to replace its interim government, Reuters reported. Police officers, many wearing black cloth masks over their faces, were seen firing at demonstrators during a march in the capital, Port-au-Prince. Both sides accused the other of shooting first. Five bodies lay on the street afterward, some with wounds in the back, and several others were injured. The shooting broke out just after the demonstrators passed a headquarters building for the United Nations peacekeepers trying to stabilize Haiti, which has been plagued by violence since former President Jean-Bertrand Aristide was driven out during a revolt 14 months ago. The demonstrators were calling for the return of Aristide, the release of imprisoned members of his administration and an end to what they called political persecution by the interim government. The clash came two days after Haitian election officials began registering voters for Oct. 9 legislative polls and a Nov. 13 presidential election. At least 675 people have been killed in gang and political violence since September. A growing number of politicians and others involved in the electoral process have expressed concern about precarious security in the troubled Caribbean nation.